Definitely a few controlling group-creators out there. The only time I've -really- seen the attention to character creation is when it's a unique species with a unique look, or 'realistic' groups. I put realistic in quotes, because some don't understand how things work in a truly realistic pack, pride or clan.
To counter the controlling people, I never enter a group with a character I made for/from another group without asking about the group first. I ask for setting (though not everybody knows what that means), if there are any character-creation limits, and sometimes plot-line. Creating a new character altogether gives me the flexibility I need to have a character without needing to worry about their backstory being okay for the group. Plus, I like creating backstories as I go with the rp, learning the character I created, as it were. Another note, I never join a group that just sends random invites out to make their group larger. I'm a big believer in quality over quantity.
Typically though, the roleplays with over-controlling owners/leaders die out quickly as people realize this person makes rp the opposite of fun with the controlling aspect.
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As far as 'mature' goes - usually it's just people that are wanting to cuss and talk about explicit activity/drug content in group; rarely is it about stuff that happens in-character, though there is that one type of group where explicit activity is sort of their M.O. Though I think those groups should be reported on the spot, tbh; it's not okay to be doing that on a 13+ game. Especially when so many kids lie about their age to make themselves appear more mature. Especially when it comes to mating.
For example, in the group I've been building, its one of the rules: Don't be afraid to say No to something you're not comfortable with, report it to the staff (of the group) if the other party keeps pushing, and the staff will handle it. The way I've built my group is to counter power-seekers; those who simply seek being in control of the group. Staff is not going to be connected to the position the character holds, but that's beside the point.
Like I said, mature means different things to different people. For most it's just adult conversation in Group, or potential for gore and violence or language use in the roleplay. They're just letting people know what they're getting into before they join, it's better that way than to under-label and then you're like "uhhh.... ig2g" /poofs never to be heard from again/. lol
