Let me explain the things from their attitude from what I learned over the years of browsing (since 2005) and contributing (since 2011). I know that some metalheads hate MA for different reasons and they have the rights to hate the site - but let's see details.
Metal Archives exist to achieve the goal of listing all metal bands from all over the world that have at least one proper metal release - in physical form (CD, LP, tape). To be accepted on MA, the band should be metal and have a proper release - available for purchasing. Since 2013 MA accepting bands with digital releases only - but those releases should be at least 30+ minutes long, available for downloading in good quality, professionally recorded and with cover art. They never accept short-lived projects that didn't release anything at least in one physical form, because if they will, every Myspace band and bedroom projects will flood the entire site.
If the band released only one demo and made only ten copies which can't be purchased - the band wouldn't be accepted.
To add a band to MA, you need to proof the band's existence (photo of a physical release / the site where it can be purchased / review in the zine if the band is very obscure) and the thing called "metalness" - that thing is the staring point of all holywars on MA.
Metal band for MA's crew is a band which no doubt is metal. Predominantly metal. I'll try to explain what it is though even moderators often had debates of what it is. To be metal for MA, the band should have metal riffs in their music, clearly heard and predominantly existed in the songs. Sometimes it's very hard to draw the line where the music is metal and where it's not. Borderline metal bands can be accepted but only if they are more metal than anything. And what MA is trying to do when they are not sure to accept or to reject the band - to draw the line.
Many 70's bands were rejected by the owners of the site - because they have only metal songs in their releases, but their albums were not predominantly metal.
60's bluesy proto-metal bands, like Blue Cheer and Cream; heavy psychedelic/occult/progressive rock like Atomic Rooster, Beggars Opera, Captain Beyond, Night Sun; classic hard rock/proto heavy metal bands, like Uriah Heep, Led Zeppelin, Mountain, Jerusalem and Steppenwolf; half metal-half hard rock bands from late 70's like Centaurus, Prom and Rhapsody Sweden - they never will be accepted because they are not considered predominantly metal.
Sir Lord Baltimore were accepted because they are heavy as Black Sabbath. Lucifer's Friend were accepted again since 2013 for being a perfect example of early heavy metal. Buffalo from Australia are also considered heavy enough.
With NWOBHM, it's hard to draw the line when the band's music is not predominantly heavy metal. Praying Mantis was brought to the site at least ten times and rejected because they're considered more hard rock than metal. It should be predominantly heavy like Holocaust, Angel Witch, Saxon and Iron Maiden on their debuts, to be accepted.
With all hair/glam "metal" bands of 80's, they considered them more hard/glam rock than metal. Dokken, Motley Crue, Twisted Sister and W.A.S.P. are there because they're heavy metal enough on their debuts (W.A.S.P. is obviously a heavy metal band).
"Metal enough" for MA's owners = having metal riffs in the music and be predominantly metal. Metal riff is the one that Tony Iommi created on the Black Sabbath debut, that Judas Priest "British Steel" is full of, that Iron Maiden opening song "Prowler" on their great NWOBHM debut.
I hope it explain the things. They are not assholes and Morrigan is not a cunt, she is a good girl, believe me. They just have no time to update all that bands and should draw the line between the real heavy metal and other music. With old-school heavy metal, it's always borderline with blues/psychedelic/occult/progressive rock/proto-punk/punk if it's 60's and 70's, and borderline with hard rock all the time. Hard n' Heavy bands are not metal bands for Metal Archives, only if the heavy metal outweigh the hard rock.
If they were Rock Archives, not Metal Archives, that problem even didn't existed. But metal music, in the opinion of Metal Archives' owners, are music that driven by metal riffs, predominantly. Old-school guys obviously didn't draw that line and didn't have that attitude. And they have right to. But Metal Archives, to being the most metal site ever existed, must draw that line. Otherwise, they should accept anything and renaming themselves to Rock Archives.