This is the brexit effect. For years thick tories wanted to leave the EU but the intelligent ones knew it would be a disaster. This goes all the way back to the Thatcher era where the establishment tories held off the anti EU loonies.
Cameron tried to shut the loonies up with a ref - hoping to win and draw a line under it.
Having voted to leave the loonies have more power, they ousted May and backed Boris and over that time frame decent tories have been leaving in droves, hence why we have a cabinet of lightweight idiots and no good candidates to take over.
Brexit has always been the idiots choice and the tory part is becoming a party of idiots as a result. No doubt the next leader will need the approval of the loonies and therefore we will continue down this road.