Eh, I think a few of the replies explain why that may be true about certain subreddits, or more accurately the behavior of troublesome users, groups, or even mods therein, but can't say that's in any way backed up by the experience of many of the largest/regional/niche/meaningful communities either.

Recommend against generalizing (which is good advice to apply to indie boards as well). I could just as easily say phpBB scrubs the identity out of many (and frankly insofar as certain sets of smileys, signatures, and other craziness "defines" other communities, in a way...it does)