Mind you it wasn't always the case. Two seasons ago when I was coaching it was subject to regular meltdowns by a mum who ws convinced her offspring was the next Messi (he wasn't) and that the coaches were "just parents anyway". She also used to regularly interrupt team talks and her special one was always five minutes late for training or games. Luckily she eventually got the hump when we repeatedly called her out on it, on both whatsapp and to her face, and she ****ed off somewhere else, thank Christ.
Few seasons ago we had a very similar situation where parents of the worst player were convinced their son was brilliant and would post asking why he wasn't picked for certain games etc. Got very awkward for everyone. Like in your case they got the message eventually and left.