Not sure if this is a valid question. But, somehow, my understanding is that when the Account's owner is updated, the Account Team Members are lost and not preserved.
I was planning some work around that to possibly fix this but during testing I found this to be incorrect and neither am I able to find some documentation related to this.
Is it possible that it was a known issue at one time or a new feature / API version that has changed this behaviour? I'm trying to remember how I came to think this was the behaviour. Apologies for the non-question
Best Answer
There is a checkbox that allows you to keep the account team when changing the owner as described here:
You might be remembering something similar to the idea out there requesting this be checked by default so account teams aren't accidentally lost when not checked:
Edit: Another idea here also states it is not possible to keep the account teams via API as you thought:
Edit 2: After testing I also confirmed that the account team is kept when the account owner changes, in the workbench, in the developer console as well as during a jitterbit upload. I found a note at the bottom of the help sheet here that does make it sound like it's expected behavior.