Comment by styanax
Hi Arathorn, I recognize your name as the core developer lead. :) Alas, when I was trying to cull my old messages I tried that (and a lot of other API type hacks I found floating around) and none of them, at that time, worked.
In short: the complete lack of user-facing easy to use controls for data retention and culling in the Matrix (Element) clients is a deal killer for me. That painful experience taught me a lesson - now when I test something new, one of the first things I look for is "how do I extract from this thing?". I never want to go through my Matrix extraction pain again, so a personal life lesson was learned.