How often does this even happen? The game really goes far to prevent this from happening. I mean they might have been super low sr/mmr stack compared to you, that has had a long long queue and not finding stacks to face against.
Keep in mind that like 80% of the stacks are like bunch of randoms who grouped up from last game or worse LFG stacks. Even those 20% where it is an actual friend group stack, they most likely are not some crazy tryhards and most likely have worse teamwork and communication than randoms.