Back in about 1996, I decided to shift my career away from music programming and toward production. That's because I simply didn't have the memory capacity of my colleagues, who can remember everything about every act they've ever heard. (A colleague of mine, when hiring new staff, would use the question -- "Tell me about an act that can really get huge with the right push, and don't tell me Old 97s.")
However, as Lefsetz points out, that's really not an issue today. While a bunch of industry insiders still engage in pissing matches about who knew about whom first, audiences use filters a little differently now.
It used to be that a music listener relied on one or two sources to learn about new music. That's when radio was King, and maybe Rolling Stone was the court jester. Today's listeners learn about new music from radio, blogs, MySpace, commercials, films, and each other. Listeners are taking the role of tastemaker away from big media, which is why it's so much easier now to "get famous" to a thousand people that will support your career than it is to get a #1 on Billboard.
When something's good, it bubbles up through a filter. Your audience is NOT digging through MySpace looking for new music -- they're responding to the things that their friends send them. So focus your attention on getting on the radar of those new tastemakers, instead of worrying so much about whether you're going to get played on the radio.