That makes more sense if you thought the parents were coaches on the team bench. That can still be a slippery slope, as you will always have that one parent who will think that coach is giving their own kid more opportunities, but that situation is VERY different than have a parent “ coaching” from the spectator stands.
Having said that, I edit my original response to say, if the parent is qualified, the school system allows it, and the interview process is the same for anyone applying for the job…I see nor harm here. I personally know 3 coaches who have coached their own kids. No real issues with any of them, all know the game, and all appear to coach unbiased.