Once upon a time politicians were supposed to be beyond reproach - for practical reasons such as blackmail, and less practical ones like attempting to not be a buffoon laughed off the international stage. I know they never actually were, but it's part of the basic job of a politician whose role is to spin, present, advocate and lead, and appearances are everything. If a politician can't keep up appearances, it makes me question their competency in the actual hard part of the job, and other people too, hence why 'scandals' tend to lead to resignations.
Now, BoJo the clown seems to get a free pass because, now that people have realised what a personal liability he is, suddenly they have to say it doesn't matter else the horse they backed will be out of the race.