If a site needs paid links, it obviously isn't as popular and/or desirable as others in the same niche
Or maybe is brand new.
15+ years ago the top results in SEs were most of the results actually. Right now the competition is immense and the mods to the various SE algorithms are continuous. I don't know what search queries you run to conclude that content is still king but the majority of searches I perform bring up very poor results.
It may change at some point and SEs perhaps realize that authoritative content is somewhat important, everything is possible.