Not speaking for anyone but me, but sometimes when people say they something is too political it really means too much "extreme" political views. Personally I don't want to interact with extreme auth-left or auth-right content. I think politely discussing why access to housing should be guaranteed by government, or arguing for lower corporate taxes or whatever, isn't what bothers most people.
Fortunately Fedi allows instances who are fine with it host those users, and I don't have to see it. And Lemmy -the project- isn't political, it's just software for which I'm grateful to the devs.