"Some" state ocean beaches ? Which state beaches here do you think MD'ing is a no-no at ? And what law/rule are you seeing that says that ? You will not find an over-arching state-of-CA park's dept. rule that says "no md'ing". Maybe a singular regional location exception at a historic sensitive monument, is all. Ok, fine, we avoid obvious historic sensitive monuments. But as for state of CA beaches (and even some inland state parks terra-firma, as long as not historically themed): MD'ing is common on all state of CA ocean beaches.
If anyone was ever scrammed at a state-of-CA beach, then it was A) a fluke, and B) some over-zealous ranger was no doubt basing in on "harvest and remove" verbiage. or C) cultural heritage (ok, fine, you're not finding anything old). and D) I have a sneaking suspicion of why anyone has ever gotten scrammed at any state-of-CA beach, in the first place.
If you can point me to any state of CA ocean beach, where it's not allowed, I would love to see how that conclusion was arrived at.