I think "go make your own group" is missing the point when discussing mechanics of the game itself. The bravery bonus streak and its impact on grouping was being discussed, so unless "make your own group" included the implied suggestion that the person making the group also write their own game code and create DDO II, it is not helpful in the least.
I agree, however, that certain subjects can be best handled by avoiding LFM's that you don't like. If someone posts about not liking LFM's that specify "TR only", they are certainly free to create their own LFM, and it is reasonable for other posters to mention that.
If the game mechanic itself was such that only TR's could see LFM's posted by other TR's, and someone suggested that was limiting grouping and was not good for the game, a suggestion that the poster "go make your own group" would be singularly unhelpful.