I think some people think that having a strongly held opinion somehow makes it more valid. The treatment that Rashford gets from some is quite nasty to say the least. Everyone agrees his workrate and attitude dropped last season along with many others. There's obvious reasons for this, a lot of which are down to him and it looks like he's trying to do something about his part in it. Surely it's our job as fans to try and help the lad by getting behind him with some positivity. The bloke stuck his head out and did some brilliant stuff for the club, the city and the country and he's clearly suffered for it. Are people really happier slagging him off than cheering him on?
Its just the nature of the World we live in at the moment and the Internet in particular, where opinions become incredibly polarised and there's no middle-ground.
Using Rashford as an example...go back two seasons (or more) and if you dared to suggest he might not be an elite talent, you suddenly received about 20 notifications within 10 minutes telling you what an idiot you are, that Rashford is better than Mbappe and that Rashford is ahead of Ronaldo and Rooney at the same age.
So then you try to respond to some of these trolls/idiots nicely with more nuanced or at least slightly more realistic, non-hyperbolic arguments and you just get abused again. So you then tend to double-down on your opinions and before you know it, you find yourself somehow at the opposite end of the argument and its become completely polarised.
If you want evidence of what I mean, pop over to the Maguire thread as an experiment and simply post "I feel Maguire has been harshly scapegoated for the collective failings of our tean defensively last season, is clearly still a good player who has been a key part of a good England side and he just needs a break to regain his confidence".
I guarantee you will have 5 replies within 10 minutes telling you you're an idiot, telling you he wouldn't get in a single other Premier League team and also explaining why every single goal we conceded last season was all his fault.
Fact is, that's the Internet. Extreme opinions and trolls dominate and suck all reasonable and nuanced arguments to one end of the spectrum eventually or at least drown them out and shout them down.