I never said real MDMA doesn't cause problems. But I don't think long-term comedowns are likely from it.
Your case is different. You have probably associated MDMA with DP/DR. Just like I have associated weed with anxiety & paranoia. I know I shouldn't be feeling anxious or paranoid on weed because that's not the norm - most people are fine. But still, everytime I smoke it I just feel horrendously anxious because I had a really bad experience once. Perhaps your time on MDMA was similar.
I know that nobody tests their MDMA. I speak to loads of rollers and haven't met one who does. I have a friend who recently brought some pills and didn't want to test them as he 'trusted the source'. I forced him to bring them over and test them. Marquis shows no reaction and PR suggests BZP. This was his first time buying pills and not relying on me and look what nearly happened to him. He nearly took a shitty chemical that was not MDMA, yet was labelled as so. The point is that unless you test it, you could be taking anything. And considering long-term comedowns really don't appear likely from just MDMA itself, I would suggest that it is either a dangerous combination or something completely different. Thus, if you compare the Ecstasy markets of the US & Europe, the USA is more dangerous as the MDMA is notoriously bad. In England if you buy crystal MDMA it is, more often than not, crystal MDMA. I've not tested one batch of crystals and had a bad reaction. Pills are a whole different matter.
In reality, the incidence of a long-term comedown from any drug is highly unlikely. Those that do have it are extremely unfortunate.