It's not just populist factions that work this way. Northern invasions will trigger an event where the top liege can give away vassal land to the Northmen and vassalise them without any input from the vassal that previously owned the land.
My main takeaway from InsidiousMage's post is that 1) the devs continue to be silent on the majority of concerns fans have about the game, and 2) if you want to be in full control, you have to be top liege in your realm and CK3 will steer you towards this so vassal gameplay should only be short-term.
Lieges love to try to revoke your land if/when they have a claim, and you don't even have to try to win elections if the top title has elective succession, the AI can (and from anecdotal experience, often does) appoint you Emperor even if you are still a teenager.
It would be different if there were in-game explanations for this kind of thing but the fact is that the current events are lazy one-offs and not sequential, I can't recall a single event chain in CK3. If there is never any follow up, how can it be anything but confusing/ immersion-breaking and ultimately a very poor medium for creating a cohesive story? In this aspect, CK2 was designed much much better as it had tons of follow-up events.
And I know the Stockholm syndrome-esque fans will be like "well just give it time, we just need DLC"; a reminder this game came out in Sep 2020, and there were mods like the Joan of Arc event chain almost immediately after it came out so why haven't the devs even tried to do something similar instead of making fart events?
I do love the game like everyone else bothering to post on this forum, getting close to 2000 hours now but honestly more than half of that is mods and multiplayer. The truth is that the more you play the game, the more apparent all of its flaws are, especially if you also do modding and/ or played a lot of CK2.