No, it's basic science. MDMA releases a shit-load of serotonin amongst other things, and as we know, serotonin is important for regulating mood, appitite, sleep etc. Therefore, when you see people complaining about how they feel this, that or another after consuming MDMA, it is not unreasonable to assume that part of the issue could be related to an anxiety loop, fuelled by the lower levels of serotonin. Some people are just more sensitive to these changes than others, and sometimes realising that you feel "a bit different" after MDMA can freak some people out, and making them think they have somehow cooked themselves. An example of this would be the intense afterglow I got after the very first time of doing MDMA, where I felt significantly different for about a week afterwards (in a positive way), athough things like my vision were definitely altered for a bit. Looking back, it would of been easy for me to recognise these symptoms as "brain damage" and start freaking out, but I just accepted it, and everything was fine.
Having had ocassions in my life where I have absolutely smashed MDMA (500mg+ doses), I can tell you that whilst at points I thought I may of cooked myself, I eventually realised it was just internal anxiety created by having not a single drop of serotonin left, and I would recover in time. A week or so later, I was on the mend at back to my normal self (although I never did 500mg+ again).
My closing statement is this: I'm not saying MDMA is without risk - it certainly has the potential to fuck you up big time if you abuse it, and I feel that to a degree, the comedown afterwards is testament to this. However, I don't buy for a second those stories about people doing 200mg and then having an 8 month long term comedown (If what they got was actual MDMA). MDMA on the scale of things is amazingly safe, and I think people just need to leave their worries at the door, and just allow themselves to enjoy the experience, rather than worrying about shit that is unlikely to happen.
Peace