lol meme but the positioning and size of the spines vs the buffalo doesn’t make this likely

What is the purpose of the "fin" then?

Display and / or temperature regulation. What’s the ‘purpose’ of any exterior adornment?

time to compare mass/cooling appendage area for dinosaurs and elephants (they use their ears for cooling).

problem.

Weren't spinosaurs aquatic? cooling surfaces like those aren't needed if you're in the water.

I’m not an expert on these, just pointing out they aren’t made for attaching large neck muscles

Obligatory:

And a cat

It was hotter back then.

This is such a paradoxical statement that it becomes like an answer to a puzzle on how to use 17 words to say nothing then.

(Except that's not how paleo art works anymore)

I know it's a meme, but when this is posted without clarification, it spreads to people who think it's real and they regurgitate it as fact

He's not an expert doesn't equal he lacks any knowledge whatsoever. He might lack the knowledge to theorise what the bones are used for but has enough knowledge to know that it doesn't work as a muscle attachment point. How is this paradoxical?

That's such a fine point to be that knowledged but just shy of being able to actual speak confidently on the matter. It means they don't have the knowledge to speak confidently on the matter that they just did. Paradoxical.

They don't speak for their own credentials and it's unwise to trust a confident statement made right after saying:
I'm not an expert but...

Its pretty common to be that level of knowledgeable. A lot of people are casually interested enough about animals and biology to have heard discussions about muscular structures that they can determine when something doesn't work. It doesn't mean they can form their own hypothesis on what a spinosaurus skeletal structure is used for, especially if he knows that even experts are still arguing about it until today.

It's wiser to trust the words of someone who knows his own limitations and admits to it than someone who confidently uses a word without knowing the meaning. You can't seem to grasp that people can have a varied level of knowledge about different things within the same subject.

You're basically saying that someone being confident about your car having a puncture is being paradoxical if he also doesn't have the confidence to say what punctured it.

How does paleo art work now? What's done differently?

Headbangosaurus

We know from the bones many things such as the weight the animal could support and how they walked indicating how they balanced. Depending on the age and sediment the animal might have even left a pretty good outline, and in highly alkaline conditions some saponified tissue would remain (completely denatured, but the shape would be there).

The creature in the OP meme for example was a hind-legged walker, so it couldn't be too front heavy and it's front paws weren't heavy weight-bearing. Just like all of it's close relatives who came before and after it.

HOWEVER! This interpretation can change! Originally only two Spinosaurus specimen were collected in very small number of bones with which to make recreations, due to difficulties in and around the region of Egypt. It can be very difficult for archeologists to make digs given their history with the region and the local extremist factions who oppose the concept of things like dinosaurs and ancient cultures. Recently a 2014 study which looked at one particular rock proposed the Spinosaurus tail was webbed, indicating it was semi-aquatic, which would have an impact on weight distribution of the animal and support the idea of a more bouyant build.

Mostly this is just an issue with the nature of science. There's fundamentally just a lot we don't know about what these creatures looked like. Thankfully, in the last 20-30 years, we've learned a lot more. We've become a lot better at finding evidence of feathers and other surface details. We may have gotten better at estimating the musculature? I'm not really sure what the current state of knowledge is here.

But the key thing to consider is that science, as a project, is incredibly conservative. Science is all about precisely defining your claims and clearly justifying them, ideally via quantitative analysis. The reason old renderings of dinosaurs look like this is that these represent the threshold of the known. They are scientific renders, containing only the details that we can be reasonably certain actually existed on these animals. You can of course go further and fill in missing details with imagination and reasonable speculation, but this will always be more an exercise in art than science, a speculative exercise. Yes, dinosaurs likely didn't have this "shrink wrapped" appearance. But what their real appearance was is a guessing game. Yes, it's plausible spinosaurus had big back muscles rather than a fan, but there are likely also other speculative models people could propose. Maybe the spine isn't a fan, but the base of some giant peacock-type tail? Maybe it wasn't a fan, but a series of spikes. Maybe it wasn't one vertical fan, but two horizontal sheets? Who knows?

Science is an inherently conservative exercise. We tend to forget this. Political conservatives hate science because they hate when reality disagrees with their dogma. But while political conservatives call science woke or liberal, the truth is, institutionally, science is conservative. Ideas move slowly. Major paradigm shifts only occur when overwhelming evidence forces them to. Ideas often take decades to slowly percolate through academia, sometimes only changing because the old generation retires or dies of old age.

Scientists as such are, generally, biased against making unfounded claims and speculation. A lot of scientific training focuses on precisely defining your claims, including the precise limits of those claims. And this bleeds over into scientific renderings. From a scientific perspective, it is often better to make a rendering that you know is almost certainly incorrect, rather than make a likely more correct rendering that you cannot support with evidence.

Some recent evidence suggests the Spinosaurus may or may not be semi-aquatic. We've got a super limited fossil record from this region of Egypt.

Party on, Wayne!