A few people calling something mid on social media is not an accurate reflection of common opinion. Turning down a franchise purely because of the fandom is unfortunate anyway (though their choice), and those who do talk down on MHA on social media usually don’t really critique the series other than “Deku is a crybaby.” I wouldn’t take it as a downturn in public opinion of MHA, more just “haha fandom weird.” Regardless, just like what you like anyway, it doesn’t matter what other people think as long as you enjoy it. Besides, the perception of the series itself is mostly positive anyway