Sure, and if Rashford hadn't been the only person pulling his weight alongside Fernandes in 2020 while Cavani, Martial, Greenwood and Pogba were non-entities for one reason or another, we wouldn't have been up far enough to fall off. Argument works both ways, despite how good Cavani and especially Greenwood were in the run-in - Greenwood had one league goal going into April and somehow received less than 10% of the abuse Rashford and Martial had been getting all season. You say you find people mocking the likes of STW triggering - go back and read the posts in that "Rashford and Martial are a problem" thread to see where it comes from, even the guy who made that thread said halfway through that the weirdos were taking it way too far.
I have loads of posts in here acknowledging people with legitimate criticisms of Rashford's game. Those aren't the ones I've been repeatedly having a go at - there's a difference between "he isn't good enough right now to lead our attack if we want to win the CL or PL" and "I'd take Welbeck over him if I needed a performance", followed by repeated straw-man arguments.
At the end of the day, there are four positions in that attack and I struggle to believe anyone could have watched the team over the entire season and conclude Rashford's is the one that needs the most immediate upgrade. If you acknowledge that Fernandes is our best and most productive player and then take in that the difference between him and Rashford this season was literally penalties, it becomes a ludicrous argument. It's fine to say Rashford had plenty of crap performances throughout the season - every player did, he had more of them than the rest in the business end of the season. Over the full season, he wasn't the reason we didn't win anything.
If Cavani and Greenwood can maintain their performances from April onwards for the entirety of next season, if Sancho (or someone else) comes in and tears it up, and Rashford keeps playing like he did from April onwards, then sure, Rashford is the problem. Right now, no.