This is only the 2nd time it has happened when a FA was persistent.
The other time I was a DH and sat row 8 with the other guy with was flying with when the FA came and told us we need to move to the back. We again said no thanks but then showed her the other 6 DH that were in front of us if she wanted to go ask them as well.

I think it's an old unwritten rule and some haven't gotten the memo it's not required yet.

However, I do believe assigned seating will be an issue.
Good thing we have tools at our disposal if need be