I do this all the time. I live in on a small island that is dominated by a very active and coordinated red team. As a blue player I have tried countless strategies to simply hold three gyms. No matter what I do the red horde has free reign to take every gym in town and still chase me out of the few gyms I want for myself. It has gotten to the point where red players park pokemon on my island simply because (without me) they could realistically stay there for months.

So I started knocking down red gyms to level 1. This forces them to waste their energy prestiging up gyms and depletes their resources. It also discourages nearby players from traveling here to put pokemon in gyms. Eventually I hope to scare off people from outside the island so that the gym scene is more competitive (there are other blue players but they have given up). I also want to change the mentality of the red players from "i saw a blue gym today and i almost threw up" (actual facebook post) to where they will be happy simply sharing the gyms with other teams.