No. "Spin to Win" happens because the mobs vulnerable to it have AI scripts that prioritizes facing their targets with very narrow targeting LoS cones and would not interrupt their current action if movement or distance prevented them from attacking their target. The mob's AI gets stuck and would therefore not progress as long as the current target could move faster than the mobs turning speed. This was fixed for the most part by massively widening and lengthening the targeting cones and attack ranges as well as changing the AI script priorities so that they would no longer get stuck. This is also why most enemy's single target casts can no longer be LoSed and so many fights now start with a Raidwide or Omnidirection/distance tankbuster.
The stuttering happens because of animation lock. Most of the games' mobs can't actually move and attack at the same time without "gliding" across the floor in a similar manner to our characters when they are doing actions with long animations.
Wrong. They don't do it anymore because they are more focused on maintaining fight consistency over multiple attempts. Stationary and self-positioning bosses are really easy to make consistent as you don't need to worry if the boss being in a slightly different position or facing a slight different direction would make a mechanic extremely easy or impossible to deal with.Responsive mobs allow for more complex positioning mechanics. You have to be able to 'pilot' them around the arena to reposition your team out of mechanics. If. The. Boss. Stops. Every. Two. Seconds. For. An. Auto. Attack. This. Doesn't. Work. Out. So. Well. There have been some valiant attempts (A7S). But FFXIV has largely just given up since Stormblood and made the bosses move for you. So now you're a lower damage output melee dps that occasionally eats a tankbuster with an invuln. Ye olde 'Move boss out of permanent puddles that gradually shrink down the arena' is pretty much a primary school level tank check, and yet FFXIV is utterly scared of that sort of fight mechanic because it highlights the m-m-m-m-m-movement jank so badly. Warcraft doesn't need to design brilliantly creative fights to outshine fights on rails with pre-programmed boss movement and timestamp locked abilities. They just need to design minimally competent ones.