Ok, armchair psychologist here - "it" came so easy to him - it being the "mastery" of existing styles - that coupled with the addiction issues...at some point he started asking himself the same questions that Liebman asked (and probably before anybody else started asking them) that a certain style of self-loathing set in. I mean, he probably knew that he could/should be doing more to move forward, but...why? And you know, I really can't, I'm a fraud (Coltrane at half-speed, remember), so fuck it, let me play like Sonny (and really if you can do that THAT well and inside it's what you love, hey...) and self-destruct, let nature take its course.
Totally speculative, and Liebman would rightfully call BS on it (he does that, you know). But really...what else makes sense? The wildcard being that things don't always make sense...they just don't.
All I know is that I have a soft spot for Steve Grossman that I don't have for any of those other guys, Liebman included. In my heart, not in my head. Some of those Stone Alliance albums are just SO full of pure, raw, feeling, not unlike a punk aesthetic as practiced by a certain time/place/people of a jazz bent. Infinitely more musical content, but still, just raw feeling.