It doesn't happen in the two worlds I commish because, if you tear it down too much, you get 1-2 seasons before you miss the MWR. But, in Foxx, we have a back to back WS winner that was left behind. An owner entered the world, took the team and announced "I've never had a payroll this high. I'm going to have to make a lot of trades!!" then left an hour later. Another owner took and just announced "Total rebuild".
The team is expensive and old. But it's also pretty good as it was built by an alias before his missed a couple of weeks and was replaced(along with his "friend" who disappeared the same day). Obviously, anyone would like to move old, expensive players for young, cheap players. But, if I thought I had a run left in it(and it looks like it does), I'd start my "total rebuild" next year.
And, yeah, it's pretty prevalent. I'll peak at world chats where I've been, that had a ton of openings or those with a commish in one of my worlds. Almost all of them have the "every veteran available" post in the first week.