I have seen people use it this way, but I have also seen people use it as a 'get out of trouble free' card (or try to), though not necessarily on FR (though I think there have been a few people who have done it).

Which is one reason why I tend to avoid people who have many of those identifiers, especially on a website that has nothing to do with them, because it often does come across more as 'I have this, so you can't chastise me for my actions' than truly 'sorry if I misunderstand something! I have X and sometimes have trouble!' (again, this is mainly with those who have multiple mental illness identifiers)

I definitely agree with the good intentions, but have always agreed with the 'the path to hell is lined with good intentions'. They can so often go wrong, and as you said, those identifiers can be used to harm the people that are using them.

Along with the idea that the other post brought up, about people using them and NOT having the condition, but only a basic understanding (OCD = obssessive cleaning of hands, or needing everything symmetrical, or being intensely clean) of the mental illness. It perpetuates the stereotypes.