I think you need to readjust your views about MDMA a bit as well as the people who use it. I’ve been to a few Dutch techno festivals and at some of them >90% of visitors are on MDMA or some other party drug. These are not stupid people. On the contrary, they are mainly the most intelligent, young, beautiful and fit urbanites. They care very much about their health and safety. You can bet almost everyone of them who read this and had this pill tossed it out immediately.
The Netherlands has a tolerance policy to MDMA. People can and do send their drugs to the government to get it tested for free and this is probably how they picked up on the polluted pills. MDMA when used properly is a safer drug than alcohol.
Side note: what is a “pill designer”?