Rock really is three chords. Everything else is window dressing or some arranger getting cute. Or Steely Dan — which some people argue is, actually, far from rock.
In the case of “Alki Point,” a simple Seattle instrumental jam from a regionally popular band back in the 1960s, it’s three chords and one hell of a Wurlitzer piano (think Ray Charles’ “What’d I Say”) backed by a spot-on rhythm section. Dig it. From Northwest Battle of the Bands, Vol. 2 (Knock you Flat!).