seconding that the first/best move to make is to unfollow the people who are putting these posts on your dash. you could also maybe blacklist the word “reblog” and/or its variations, because the discussion on “liking posts is Literally Evil” tends to compare it to reblogging, and “reblog” is a less common word and therefore would be less likely to catch other posts up in the filter if you do blacklist it.

that said, I don’t know of any extensions that do this that currently exist, but the currently-supported version of xkit is “xkit rewritten” by tumblr user april and I believe that she has a suggestion box for “things people want to see in xkit” available somewhere, i think on the project’s github.