A paid seat request cannot be guaranteed, as it may need to be changed for operational, safety or security reasons, even after boarding the aircraft
As far as I can determine, this thread got heated when mad_jock (
nomen est omen) started equating asking a question of the cabin crew with "backchat", the latter being a valid reason in his parallel universe for his having a passenger disembarked.
It's now evolved into threatening to gift customers a criminal record for "backchat....
Again.
If cabin crew give a legal instruction, there's no reason
not to comply.
If it's a "you'll do that just because I say so", there will be a request for explanation.
And if you assign me a seat other than the one I've paid for, I'm certainly entitled to ask politely which "operational, safety or security reasons" necessitated the change.
In the hope that the captain - if he or she deems it necessary to get involved - acts like the senior management that they are and not like a jobsworth municipal parking attendant....