What concerned me about that particular Ask Riot post wasn't so much that URF caused players to stop playing League (that's understandable, and well-explained in the post), but that after URF, players would stop playing League permanently. This isn't something that can just be chalked down to the post-binge churn, because those kinds of hangover periods are temporary and are usually quickly recovered from (experiencing a literal hangover doesn't usually make people quit drinking forever, for example). Because of this, I think the analysis is not only flawed, but also highlights a much deeper problem with League: some players are likely playing out of habit and sunk cost, rather than out of genuine enjoyment, and quit the moment they get enough distance to realize this. Effectively, this would mean that URF itself wouldn't be the problem, even if it would act as the catalyst to this kind of burnout.
I don't think this kind of phenomenon applies to every player, or even the majority of players, and I also think this is a hypothesis that would likely require much more actual research. The fact remains, though, that that Ask Riot post gives a reasoning that doesn't accurately describe the full problem at hand, and that similarly doesn't come across as particularly good justification for releasing game modes that are, by that post's own admission, just worse versions of URF. If nothing else, that post's conclusion also highlights another problem with Riot's approach to League, in that they struggle to provide consistent support to any game mode other than classic Summoner's Rift.
If the problem is that some players only want to play URF, then this may in fact be a golden opportunity for releasing URF as a permanent game mode, one guaranteed to have a consistent playerbase, yet by Riot's own admission, they don't balance URF, and don't want to balance it in the future. This dooms every one of its successor modes from the start, as the ongoing lack of polish essentially guarantees that any subsequent variation of URF (as well as most other rotating game modes) will very quickly devolve into a highly rigid and unbalanced meta, sapping the fun out of it within days, even hours, and forcing Riot to either start over or pull the mode until players forget it (and players don't really forget). I genuinely believe several of League's rotating modes, including URF, have the potential to be successful and viable in the long term, if they were to receive just a little bit more dedicated balancing. Until that happens, though, RGM queue is bound to leave a sour taste in player's mouths once each mode's particular meta gets solved.
