Paleontology has always been a competitive science with competing schools of thought trying to push their theory to acceptance.
My personal belief is somewhere between the two competing theories. I don’t think they were completely gone but were nearing extinction all by themselves. The fact that mammals were already on the rise seems to suggest that they were filling vacated ecological niches.
I also have problems with the animals that survived. Not all were aquatic dwellers or burrowers. Even some aquatic dwellers like alligators are shallow water dwellers and would have to survive years of super heating or super cooling depending on the global effects. Lots of insects that aren’t burrowers or swimmers survived.
I think it was a real bad time but not as bad is the impact extinctionists need it to be to exterminate a world full of dinosaurs.
With the Dino-Asteroid theory unfortunately politics and the media got involved. It kind of caught fire with the anti-nuke movement in the 1980s (Nuclear winter killed the Dinos so just image what it can do to you kids so join us in stopping Reagan) and it’s used a lot to try and re-ignite the myth of the noble savage (If a meteor killed the dinos then maybe one or more killed all those animals instead of the peace loving ancient humans).
It also has a coolness factor, the dinos just capture our imagination and being wiped out by a meteor just has that great Hollywood type ending.
Those things keep the impact hypothesis going, despite the mounting evidence against it.