it's not the Doobs fault (line) that they sound like Santana on this one.
Say what you will about this part of the 70s, there were more jazz artists crossing over around then than about any other period I can think of in my life. Chuck Mangione, Weather Report, George Benson, Jean Luc Ponty, and so forth. Not to mention rock bands moving the other way--see also Steely Dan, Doobies, etc.
And then there was the antithesis of that. BOS4 THeads.