You might be right that this motivates the 'euphemism treadmill', but if so I think that's misguided. It's my personal belief that the stigma follows the condition itself (particularly when untreated), not the name given to the condition. When I was a kid my friends and I all knew that you had to step light around some people's fathers because they were Vietnam vets with hair triggers that would go ballistic for seemingly little reason. In retrospect these men obviously had PTSD, though as kids we knew it as 'He's an asshole because Nam fucked him up.'
To be clear, I don't think the nomenclature is the sole driver of social stigma, just a contributor.
As an analogy, I doubt anybody thinks the social stigma around trisomy-21 is solely attributable to previous politically incorrect terminology but continued use of those former terms doesn't help alleviate that stigma.
