That's a rather sad view of what makes for good music. The last I checked, with or without radio play Tom Waits still sells millions of records and lives quite well as do any number of other musicians who don't get played on the highly commercialized radio stations. By that definition of greatness, then Britney Spears is the greatest artist ever and are we really willing to make that claim?
I have nothing against Jimmy Page, I love Led Zeppelin but I don't think he is the end-all-be-all of guitar players. The same with Gilmour and Clapton. Great? Yes. Greatest, no. I also think they'd say the same (and in several cases, they have). That they get played on the radio doesn't make them great.
I'd also mention that an appeal to self-defined expertise falls on deaf ears. It's a fallacy to suggest that you have some knowledge the rest of us aren't privy to because you are/were a musician. Not to mention that I've played music long enough to have some clue of what I'm talking about.
But if it makes you feel better to think we're ignorant and you're the expert, go right ahead.