I support Anarchy factions exclusively and I've never had to commit a crime or become a hitman to do so. FDevs simplistic take on Anarchy factions is like a steering wheel in my pocket, it drives me nuts.
I've flipped plenty of systems to Anarchy control but because I target systems with specific features I have never done any assassination or massacre missions, ever. I'll do CZs but that's different because a) it's a war and b) Anarchy's have no choice in that matter, it's their only option. I suspect if I went out of my zone for selecting systems I'd run into trouble but I don't, so I don't. I'll always leave Independent systems alone unless they expand into a system that I've worked on.
Anarchy's are not criminal per se although obviously they can be. The Federation is criminal, the Club is criminal, Sirius Corp. is criminal... and the list goes on. Criminality is the domain of big oppressors. Look at most systems, who's generally at the bottom with 1% influence? Supporters of Anarchy's are spread pretty thin in E|D and as player factions spread and new ones appear it's the Anarchy's who lose out, every time.
I happen to like rooting for the underdog so I help where I can. It's pretty much why I play Elite although even I have to take a break from it from time to time. Constant battling against the odds does take its toll.
Just to be clear this is an in-game role playing thing only. In RL I'm pretty far from an Anarchist. Call it escapism with space ships. I like space ships.