How combat que works is a crucial part of the design for turn-based combat. Larian has been exprimenting with different systems.
Their previous game, D:OS2 would intertwine teams
one character at a time - one yours/one enemy/one yours/one enemy etc. That provided a nice regular pace between player and enemy turn, but allows for little interactivity between characters. And of course, is hassle free to coop play.
The DOS 2 initiative system of ALWAYS alternating between one of yours and one of the enemies was one of its most criticized aspects after armor system and itemization, incidentally.
For several reasons, but above anything else because many felt like it was robbing characters that invested heavily on initiative-related abilities and stat of ways to leverage their qualities.
XCOM, that someone else mentioned, is a whole different beast.
That's basically "Alpha Striking: The Official Game" and the entire gameplay loop there is tuned around the idea that when your team act, it's supposed to wipe the floor with anything moving or breathing on screen before passing the turn.
When you are passing a turn in XCOM and something is still able to shoot you back, you already made a mistake.
The same type of initiative was something Larian proposed before the EA even started but thank god (or whoever covers the role) they reconsidered it quickly because I can hardly think of a worse fit for D&D.
