The OP blames "various idiot web 'designers'" for problems, but in my 30 years of being a web designer I have yet to meet one designer that wants to cause these problems. It's usually people responsible for generating revenue.
The web designers and developers are at the very least complicit. They are ultimately the ones typing in the code and hitting submit, so they at least must share the blame.
True, I'm just saying I don't think that's where the problems originate.
In my practice, I'll try a Jedi mind trick, e.g. "Trying to [state larger goal] makes a lot of sense. An even more effective way to do that is to [state alternate, non-toxic technique]."