Well half or more of the playerbase is usually busy with other things in the game or simply afk.

Anyways, being scared has nothing to really do with it.
It's just easier to join the "peaced" gangs and earn your gp that way instead of spending time attacking them.

If the amount of bases decreased you would see an insane increase of activity on the ones left over.
I'm not saying they should remove bases because there's honestly no problem with gangs peacing, it's just playing smart.