I've definitely seen that happen numerous times, with the most recent in my memory being about one of the lesser-known hardware wallets.  It's obvious when a brand new account does this, and I usually tune that crap out.

That drives me nuts, because sometimes members will start a legitimately interesting thread and then they just abandon it without participating in the discussion they presumably wanted to spark.  Another thing that drives me even more nuttier is when a member (usually a low-ranked one) solicits opinions about an issue and doesn't give their own input.  What ends up happening is a thread is started with basically a one-line post which sometimes you can't even understand.

All that aside, I thought Theymos wasn't keen on restricting newbies--I remember quite a few threads just like this one with people wanting the "newbie jail" brought back and all sorts of other suggestions, but they all died off with nothing being changed.  And I don't know, the forum doesn't seem to have gotten much worse in the past few years, and especially since the introduction of the merit system.  There's no longer a forum-wide crisis of shitposting like there was leading up to Jan. 2018, so I doubt Theymos would even consider newbie restrictions.