2) Why haven't they banned all porn games then they banned porn game X? -> it takes a lot more effort to move the needle here. It's not for lack of trying or lack of will, it's that it's obviously much harder to get traction when you've expanded now to an entire category that includes borderline mainstream titles that will finally get defenders willing to put in the same effort as them.
3) Why haven't they banned GTA when they've banned porn game X? -> First, they've tried!. 2nd, again, same principle -> activists aren't stupid, they know they can win the battle one game at a time, and that they can't win it in one gigantic decisive swoop (conveniently enough though, you can leverage this as well to ensure you have a nice long runway to continue to do your activism and keep it as a wedge issue to push at for a nice long time)
4) Why not ban true crime podcasts when they've banned porn game X? -> see again, look, many. many people listen to true crime podcasts, and many people have also objected to them as exploitative. but why does porn game x get banned and true crime podcast Z not? because, well, duh, again, the amount of effort needed to move the needle on something many people enjoy is that much more! i don't think they don't want to, mind you, but again, it's going to take a lot more effort to get to true crime podcasts when they have a thousand other porn game XYZ's they can to work on
And lets not pretend people aren't also trying to get books banned, again, it's being done at a more selective pace, book by book, not category by category. Why is <random niche hentai> banned and not <50 shades of grey>? well, who is published by a mainstream big publishier and who is published by a niche publisher that doesn;t want to get the whole hammer on them?
Repeat at nauseam.