The hard lock of not being able to change markers in-combat was more of a loss to the general player base than the raiders. Most of the time people used it in a way of pointing out 'go here' in the middle of mechanics or what will be the safe spot we should move next to for newer players.

It's no different than back in the days of T9S. I had the down time during mechanics to look at the dragons and move my mouse to place the safe spots for divedomb markers. Players adjusted since with UCoB standard markers. Nonetheless, it was a dumb move to hard lock them because here we are today and it really hadn't changed anything from a prog raiding mindset, nor it does for TEA.