Yes, a large amount of people the world over enjoy "ITM" (ITM, as you put it. eeeeaaauughh what a hideous abbreviation that I've never once heard from anyone who was actually any good at playing traditional Irish music).

Yes, a lot do come to it via Comhaltas. And a lot come to it via commercial recordings and Celtic Women and Riverdance etc, and a lot come to it through places like thesession.org. But non of these are good enough resources to enable players to become any good.

So, the astonishing thing about the robustness of traditional Irish music is that despite the vast majority of people the world over who do enjoy playing it, but play it deplorably badly, it still survives, nea thrives.