It's not either/or.
One badly speaking fucker doesn't exonerate all others. Rather, it should shine a light on all those who ham up their accents and awful speaking tone.
Once recognised, the next question should be: why are they doing this, acting, putting on this awfulness? Why do they feel that certain aspects of themselves have to be exaggerated , even caricatured?
Do they think that their chosen persona-posh upper class twit or daughter of the slums might not quite reach those sitting at the back?
It's always interesting to ask why someone strikes a false note
Of course, there will be those so blinded by love for a posh upper class twit or a daughter of the slums that they won't do this or suffer anyone else to do it-they will always jump to their defence.
That's fine-it's amusing to see the defences brought out but most people pause and wonder why they do this and there is always a why.
Personally, if someone hams it up to the extent that are at worse, renders them practically unintelligible and at best, an assault on the ears-they should -at the very least-be laughed at.