Hmm. Well, first of all, I aready said that I didn't say Kenny Loggins was great, only that his ONE song titled This Is It is one of the top 10 of the 1970s, but since you brought up this comparison thing, let's see what the facts say:
Kenny Loggins Awards (Note that for awards mentioned more than once, that means he won that award more than once):
Best Original Song
Best Original Music
Outstanding Special Class Program
Outstanding Original Song
Best Original Song
Best New Artist
Best Score Soundtrack for Visual Media
Song of the Year
Best Male Pop Vocal Performance (this was for This Is It)
Best Male Rock Vocal Performance
Best Rock Performance by a Duo or Group with Vocal
Best Score Soundtrack for Visual Media
Best Male Pop Vocal Performance
Best Male Pop Vocal Performance
Best Musical Album for Children
Best Musical Album for Children
Best New Age Album
Best Original Score
Drive-By Truckers awards:
Best Pop Instrumental Album
So, I think Loggins wins there. Also, Loggins' net worth is listed at $16 million while the lead singer for the Drive-By Truckers is $1 million.
Loggins is past his prime of course, but he was a big deal in the late 70s and 80s, writing scores for major motion pictures, charting high. Your comparison just doesn't work here at all.