How is /r/t_d different from /r/theredpill or any of the other racist/sexist/terrible subs? I haven't really seen any overflow in a lot of the not-default subs, but it could also be the subs I visit. I mostly stick to subs for games I play, programming, and a couple BP support subs.
For me, the crucial change of how I curate my subs happened when 2x became a default. I hated the sudden influx of bad posts, mansplaining, and terrible/abusive comments.