It completely ignores the fact that ease of access to information is a greater determinant of what people learn than existence of information.
Yes, right now it is possible to find discontents of a brand or company by searching and reading through various forums and webpages of differing quality and structure.
However, if there was an easy mnemonic like "just add .sucks to the end of a name" to find the bad things about $NAME then the game would change. It'd be easier for people to organize and oppose companies than anything else imaginable.
And that makes a huge difference. Think of how hard it was to find programming help before stack overflow. This would be a much more potent and wide-ranging way to organize information, because it can still be difficult for a novice to understand what to search for on stack overflow. This would remove even that last bit of friction.
I'm not denying that .sucks is a bold and roguish move. I am asserting that it is an effective move.