Literally what I just said: actions aren't executed in sequence in a RTWP, in a queue; they happen all at the same time.
Because it's supposed to be a "stop, plan, and go", not "play in real time clicking really fast".
It's not even an unique prerogative of Baldur's Gate. RTwP is an entire genre of games that ranges from RPGs like Darklands, BG, Dragon Age and Aarkash Legacy to things like XCOM Apocalyplse, Commandos, etc.
Look, you are talking to someone who prefers proper turn-based to RTWP in nine cases out of ten and I still think this argument is complete bullshit.