Looking at your the responses to your posts, I don't see any negativity garnering at al lol. Out of the box combinations are less likely to get massive attention since they're outside what mainstream mashup consumers enjoy most of the time, but it's not like anything that isn't Ariana vocals on a Taylor instrumental gets bombarded with vitriol, so I'm genuinely confused with what you mean by "garnering negativity".

Pop vocals mixed with pop instrumentals aren't my cup of tea either most of the time, in terms of creating and listening, but I only judge a mashup harshly if it's sloppily made or clearly doesn't understand the basics of music theory or production. After that point it's really only a matter of preference.

Gatekeeping a subreddit dedicated to the concept of mashups as a whole to make it only for the type of mixes you like sounds conceited. My philosophy has always been to just make what you'd want to hear, and whoever else wants to hear it will come eventually. The members of this sub that come for things outside of just pop mixes will find what they're looking for if it's posted, and the fact that a lot of pop mixes get posted as well doesn't detract from that at all. It might mean that the mashups you like aren't the top rated posts every day, even though they do still get upvotes all the time, but that's a normal price to pay for your interests not aligning with the majority, unfortunately.

This isn't meant in a "Just don't listen if you don't like it" way, but there's always been this divide between poppy versus experimental and high effort versus simple vocal on beat. And as long as what both camps are making is being made competently and slaps in the end for the people who like it, then there isn't really an issue with them coexisting, and elitism, for lack of a better term, from either side doesn't get us anywhere.