Is anyone here familiar with the Simming communities of (mostly) the 1990s? Freeform roleplaying, sometimes with a GM in charge? The Star Trek Sims were huge. They never had any mechanics for task resolution, but seemed to manage.
If I may bring in something peripheral, but possibly related?
Many years ago I was involved in mechanics (though not definition) free MUSHes, most of the superhero based. Most of these were consent based; much of what was going on that involved conflict involved other players, and while you could declare whatever action you wanted, it was up to them what result (directed at them) you got. In addition there were oversight individuals who, when operating in that mode, could intervene under some circumstances.
It was, to me, extremely instructive about the strengths and weakness of such freeform (at least semi-) roleplaying.
At its best, it could produce extremely interactive and interesting combats and events where all participants understood how each other's characters were defined (usually with various sorts of benchmarking), and had at least some concept both how combats in the genre and to some extent reality worked, you could get a nice narrative interactive scene that was honestly a lot of fun.
That was the best of the situations.
At its worst, you have people who were unwilling or incapable of engaging with how each other's traits worked, had an overblown idea of what the benchmarking meant, were carrying around questionable ideas of how combat worked, or otherwise were extremely unlikely to engage properly, the scene would go, well, terribly.
Now, you might say "Well, that's the problem with the lack of a gamesmaster."
But the question is, would a gamesmaster (which would be present for bigger, more plot driven events on occasion) necessarily be any better than the second group of people? If they weren't, instead of simply ruining the experience for a small number of people, they could ruin it for a large number.
Because there was an overall group administrative structure, there were things that could keep this down to a dull roar, but that created its own levels of controversy (questions of favoritism, accusations that the admin didn't understand the characters and genre and more).
Now, this is not exactly equivalent to true freeform text or chat roleplaying, it wasn't far from it, and my observation was while they "managed" a lot of the time, that was because they people who didn't have a particular group they were interacting with that were on the same page would either go limp and not do much, or leave. It hardly seemed to suggest the approach was, overall, a resounding success. And I stuck with MUSHing for a number of years before I gave it up.