The body positivity and health at any size movements have gone far off the rails. It went from, "Don't be a dick." to "This is beautiful and healthy."
As The Drinker put it, The Whale isn't about obesity. It's about addiction and self-destruction (among other things). He could just as easily have been a drug addict or an alcoholic. The thing is, nobody would have said anything about the depiction of an alcoholic drinking himself into an early grave, or demanded that they cast a real alcoholic in the role.
Yes, I do believe that zero people would have had the same gripes if Leaving Las Vegas were made today.
Any of these gripes about how disgusting the imagery is in regard to Charley's addiction, and what it's doing to him have to be coming from people who have never experienced what it's like to be close to death do to your addiction.
I've been in the hospital three times from alcohol. Leaving Las Vegas looked fucking gorgeous in comparison to what drinking yourself to death actually looks like. Imagine that last scene with Nicholas Cage surrounded by buckets of vomit, himself covered in vomit, not to mention that he would be vomiting well after he emptied his stomach, so much of it would be acids and blood. That's what it looks like.
What they depicted in The Whale is probably pretty damn close to what it looks like to have someone eating himself to an early grave. It's not pretty.
The only reason why people are pissed off at this movie is because it shows the real consequences of an unhealthy lifestyle that they've deemed to be off limits in regard to legitimate concern.