Perscienter: They could have written a much better AI in 1998. It's not a good AI because the soldiers constantly hit obstacles and kill their allies with mortar fire. It's an unfinished AI and you can easily exploit this.
Waltorious: I honestly don't remember seeing soldiers get stuck on objects or killing each other. But I could be misremembering.
I have a feeling I played the demo for this game several years early, which may be part of why I have that impression... I'm almost certain I knew about Outcast before the original Half-Life, which actually came out first. I didn't play the full game of Outcast until recently, so my demo memories probably have me thinking it's an older game than it actually is.
And I did a mistake. It's from July 1999.
I sought a clip and here it is:
https://www.youtube.com/watch?v=XDjmvljNxI0 Start with 12:35 and pay attention to the soldier in front of Cutter Slade. He'll hit the box. Then he moves towards Cutter and he receives friendly fire from the mortar soldier, shortly after he shoots at the hill.