Nirvana made a bundle doing this. Even if it didn’t contain any unreleased material,demos or live versions, fans/collectors would still buy it. Some of them were only released in other countries so may have had something to do with a promotion or tour. There was no iTunes so this was a way for bands to cash in. Not to mention all the money made by record stores selling bootlegs. The music business was far more lucrative in the 90’s.