Not a goady thread at all, genuinely do not understand the terminology but I see it on mumsnet and elsewhere a lot.
People say 'I have mental health' but to me this seems like an unfinished sentence.... should end with 'issues/problems/conditions' etc.
We'd never say 'I have physical health' we would say I have physical health conditions and then maybe discuss them if relevant.
Where did this phrase come from? I'm quite an open person so I'd probably say 'I have depression' but for those that just say 'I have mental health' why do you say it? It makes no sense. Health is something we all have - health problems or conditions we may not all have?!
YABU 'I have mental health' makes sense
YANBU you're right it makes no sense