Ecstasy was being tested for theraputic uses before it was outlawed, including
couples therapy.
Ooh, didn't know they were testing again, cool.
If you haven't done the drug you may not understand why it could help you during a counseling session. E makes you extremely empathic, and I can see how relating to others under the influence could help you reach breakthroughs. I'm sure people may think that alcohol also makes you empathic ("I love you, man!") but seriously, it's nothing compared to how you feel about the people around you while you're on E.
This "benefit" is much different from the medical marijuana uses, which are basically a new way to tackle pain. Using drugs for psychological benefits is so standard these days though that I"m surprised people still question the idea when applied to recreational drugs. Geez, so many people use Zanax for fun...
I can see a mental benefit to using LSD or shrooms. It really depends on what you want out of it. Some of what these drugs can do reminds me of the Hofstadter stuff. It gets
meta, where you're thinking about thinking, pondering about pondering. I worked through some issues of my own in my experiences, in many different venues of thought.