Coach assigned grappling partners leads to injuries

Hey guys - so, I have noticed a pattern with the 2-3 times I have gotten hurt in the past year of BJJ - GI and no-GI, and every time it’s been when a micro-managing coach who doesn’t understand dude-rules, stops our natural pairing - with guys we trust and know, and orders us to pair with someone else.

Why is it not obvious to coaches that paying members of the gym choose partners they know and trust to avoid injury?

We aren’t talking about some awesome UFC match up - we have day jobs, and telling someone to fight for 6 minutes with someone they didn’t choose is a bad idea.