I don't really see where tripfagging could possibly be pointless in your scenario. If you aren't writing, arting, roleplaying, or engaging in a discussion with multiple parties, what the heck are you doing? I think it's a ban even for anon to post multiple threads that only they post in. Are people tripfagging, and then posting entire threads worth of nothing but talking to themselves? I can't say I've seen that before.
Anyway the sticky says nothing about "engaging in a discussion where there are multiple parties" so that's still not allowed.
What I'm saying in my second paragraph is that a PG-13 requirement in /oat/ and a ban on tripfagging in /anon/ is mean and not nice to tripfags who want to post stuff that might be PG-13 or higher.
Even if tripfags want to go anon to post R+ stuff to /anon/, they still have to go through a lot of trouble to remember to delete their trip only for /anon/, and replace it when going to any other board. There is about nothing more frustrating than posting Original Content on /art/, only to realize that you erased your trip to make /anon/ happy so your name doesn't get on it. And really, tripfags shouldn't have to switch to anon and post on /anon/ at all. /anon/ is for anonfags, not for tripfags forced to anonymize themselves. But since /oat/ won't let you do #Mature threads, /anon/ gets misused that way.