This doesn't match my personal experience at all. I'm in my 40s, husband is in 50s, both took massive amounts of mdma in the 90s and 2000s, way above the guidelines you are describing both in terms of single night usage and frequency, and still do today but much less frequently. Large cohort of friends with similar histories. We seem fine. Husband is about the most naturally happy, well adjusted person you could meet and his consumption of mdma at times was sort of over the top.

Ymmv!

It absolutely does screw with some people's mood for the worse, but definitely not everyone, or even most people. I do think for people predisposed to depression and anxiety, heavy usage can be a bad triggering or worsening factor.