I've had that kind of reaction - on rebases also - and most times it was in fact a code smell pointing to a case of spaghetti code.
If you get to the point that you fear upstream merges/rebases into your WIP, stop for a second and ask yourself if maybe that might be an issue with too much interpendencies inside the code itself.
Code should be as close to an directed acrylic graph as possible. (doesn't count, I was not speaking of git! :b )
A merge from upstream once a day, at the beginning of the day.
I'm working on a DevOps setting, and even though we're a small team, we have about two to three changes going through the pipeline a day.
If you keep your fork too long without syncing, it just get more complicated to merge, and more importantly if you need help from the upstream change author they'll have moved on to another subject and the change won't be as fresh in their mind as if you had merged the day after they pushed it.