orbis

That's a simplistic way to look at it.

There are lots of people out there that don't own any Iron
Maiden studio albums on CD. Plenty are old fans who owned
original LPs or tapes, plenty are new fans, plenty have heard
"Run To the Hills" on the radio. To these people a greatest
hits album is an infinitely better introduction to the band
than buying a studio album.

And it is for this reason that record companies release
greatest hits compilation albums.