Alex, thanks for the clips and for sharing your thoughts. Some more of mine:
Context, context, context. Very important when trying to find answers to your interesting questions. Btw, I think it's wonderful for music lovers to look at these issues; puts the work of favorite artists in a better perspective and gives more insight into the music.
Something that isn't always given enough scrutiny when looking for answers to these questions is the role of the producer. Every recording lists a producer. He is often the guy that says: "Hey, I know this good, or promising young guitar player. I want to record him. I think I will hire so and so to back him up on the record"; or, even, "Hey, Milt Jackson is really hot right now. Pablo records has him on contract. My label Slick Records doesn't have a vibes player on the roster. Who can I get to fill that slot and capitalize on the current listener interest in the vibraphone?". Given the relatively short supply of jazz vibraphonists, he may end up recording a second tier vibes player. The point is that simply because a player has a record contract or records with top tier players does not automatically mean that he, himself, is a top tier player. I know it takes a bit of the romance out of it, but most of even the top players are "guns for hire". Of course, the great ones will not play for a lame "leader"; but, that leader may sometimes not be on the same level as his sidemen.
I cannot think of one single example of a player who was "the one" and then simply disappeared from the jazz scene. Sure, new players and new styles come along and supplant, in general level of popularity, the older player. But, any player who is "the one" will have, by definition, a substantial body of recorded work and that will live on; in the context of general declining interest in the art form. Example: Joe Lovano is probably "the one" right now in the tenor saxophone world. Does that mean that Sonny Rollins (who is still alive and playing) has been forgotten? I don't think so! Re your clips:
When you refer to these players as "equally as good" as the high profile players, what higher profile players are you referring to?
Thornell Schwartz. My first thought was, here we go again, nice and easy twelve bar blues. Says little about the player's range. Even in that context, and compared to someone like Kenny Burrell, a mediocre player. And that tenor player!? Ouch!! Sorry.
https://m.youtube.com/#/watch?v=dIZQYzQorucRay Crawford. Nice player. Still, compared to, say, George Benson or Wes Montgomery? Not quite.
https://m.youtube.com/#/watch?list=PL8DB57484F40BBCC3&v=SLG2ssX2otohttps://m.youtube.com/#/watch?v=AbXHRF8D7agDempsey Wright. Best of the three by a long shot; albeit in a very different style. Very nice player. Still, compared to Joe Pass or Herb Ellis and, well.....
https://m.youtube.com/#/watch?v=_RPkohp10EQSpeaking of the twelve bar blues:
https://m.youtube.com/#/watch?v=3muZKOxqtGUDebate is a good thing. I'll stick to my contention that, by and large, there is usually a real reason that most players who are forgotten are forgotten and some remain in the limelight (or in record collections).