Some have already been posted, but when we were doing the decades thing, I ended up with this huge list of songs from the 1970s, that were on the radio and I liked generally I suppose, but sounded quite a bit alike (given the nature of the songs YouTube puts out there for you). So I posted almost none of them. Nor were they really representative of what was playing on AM radio in the 1970s, which might typically have 2 Beatles’ songs per hour, Rolling Stones, Kinks, etc., and older songs. Disco I was never a fan of, though many songs then shaded into that (including by the Rolling Stones).
Going through them now, keyboards factor in more in the 1970s than the 1960s. But they are not necessarily “primary” or dominant.
This first one below is somewhat like that, which I am posting as an example. You hear it a lot at first, then it tends to blend in with everything else. Listening again, the last one probably too (the 2nd and 3rd the least so).
But these love songs were the ones with the most dominant keyboard from among all the ones on that huge list (other than ones others here have already posted).
1977
1968
1969
1972
1975