I've not seen "people blindly defend".
People come in and voice an opinion - "this game's shit, this dev's a crook/milker", etc.
Those types generally just get facts presented that disprove their opinions. They also get mocked, rightly so.
The people that criticise, "I think this game is shit, because.." will have their justification examined.
If their justification is sound, or is a matter of personal taste, no-one can dispute it.
If their justification is contrary to known and established facts, then it gets rightly disputed.
The people that constructively criticise, "I think this game is shit because, here's what I think would make it better..." are also subject to the same justification check, but these are more likely to spark productive conversation.
As for it being "a valid concern", it would take 30 seconds to search for the information which either corroborates, or invalidates that concern.
People are quite capable of finding the information, for themselves, to make an informed opinion.
They chose not to, then complained about something which had already been explained & justified.