Can anybody name a single series of this premise where the split is amicable? The closest thing that comes to mind is where the party forces their workaholic tactician to "investigate" rumors of monsters at a hot spring city, but that's just a temporary departure from the team for narrative purposes and, well, entirely different.
It's always so extreme-- literally throwing the guy out, trying to kill him, abandoning him in combat, somebody forcing a schism in the team, etc. This one more than a lot of the others could've been resolved in a clean fashion: The guy knows he's pretty limited in scope and acknowledges that he was kept on mostly as a courtesy to a more valued member of the party. "We took a vote, a debuffer no longer fits into our team, here's your share, good luck, now go away." and then he took his split, walked off, and absolutely nothing else is different. (They could bring up the whole thing as a major plot point later, but seventeen years is a long time to hold a grudge especially since nothing happened. Hell, even even acknowledged he's good at his super-specialized role... that's just no longer useful at their tier.)