I know there are alot of posts on this sub explaining that shermans were great tanks, many of which I read and knew the points they make even before I read them, but why are they seen as bad?
Is it because of survivor's bias, or rather it's opposite, the corpse bias, where bad experiences make more of an impression that good ones? Is it because of the book "death traps"? If so, why did the writer see shermans as bad tanks? Or are there other reasons?
I'm sure plenty more can be said, but I found some previous answers that might be of interest to you. There's a section about the Sherman and Allied armor in the FAQ. /u/TheHIV123 also wrote a very thorough evaluation of the Sherman here.
Of course, where the reputation comes from was not directly addressed in those links, and I'm sure that has a history of its own that's waiting to be written about....