Because, all too often, those comments are not prefixed with, "I haven't used Language X, but I hear that". Instead, they masquerade as comments by someone with

Because, all too often, those comments are not prefixed with, "I haven't used Language X, but I hear that". Instead, they masquerade as comments by someone with actual experience. The poster knows that if they were to add that disclaimer to their statement, it would lower the credibility of what they're saying. And we all know you gotta be Right On The Internet, not intellectually honest.