As a freak music fanatic there are a ton of albums that aren't on Spotify, a lot of foriegn ones specifically. I happen to love Nekromantix as well, but a lot of the older stuff from bands like that hasn't made it on the app yet, and a lot of it may have to do with album "rights"; the possibity that the earlier albums were under a different label or something. Regardless, Spotify doesn't just take music and put it up, there is some kind of agreement to have the music up (sorry, don't know the specifics). As a Nekromantix fan you may not have heard/cared about this but I know like... Taylor Swift and Beyonce pulled their music from Spotify, so it's really up to the artist as to what is on Spotify as far as I know. I'd really like to have Behemoth's first album and some more Ensiferum amongst some other metal albums, in addition to some rap mix tapes (Meek Mill has like 5 mix tapes that aren't on Spotify) but hey, I'll live with what's on there now. If you'd like that older Nekromantix stuff really you should contact them and tell them to get in touch with Spotify about putting it on.
It's worth bringing up though, I might make a thread of "missing music" that people would like to see on Spotify, but like I said, I don't think it's Spotify that 100% decides what's on the app.
Also, it may be the version of Spotify/the location you're using it from. I lived in New Zealand for a while and there was quite a bit of music I could listen to there that I can't listen to now (back in the US), and vice versa there is music here that I couldn't listen to there. No so much entire albums missing but sometimes under an artists there are songs that are unavailable. I'm not sure that you can do anything about that, I'm just bringing up the fact that maybe in your location that album is not up but may be up in other locations.
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