Yes, I agree with that. And I certainly find a lot of people I know had to understand, specially those of this parish of a teenage flavour. But I think we need to guard against feeling that if someone habitually uses sounds that we personally find harder to understand than, say, RP, this is necessarily sloppiness or laziness on their part. It could be a bona fide local or community accent, and/or part if the 'continuous improvement' process.
It was the statements which seemed to suggest that there were 'acceptable' accents and 'unacceptable' ones which I was disputing - specially as people seemed to be dismissing some forms of speech (such as the 'r' in question) which are certainly not sloppy, just different.