So, now what? I still think this is further evidence of a MFiT not being a different release than Spotify, just because of that. An example I’m really starting to notice is that all MFiT releases that share their Apple IDs with Apple Music, don’t have a MFiT blue badge on Apple Music but only on iTunes. They share the same barcode, because they have the same Apple ID. If Apple doesn’t even acknowledge that MFiT is a different release than the Apple Music (one which is identical in barcodes, artwork, etc). Shouldn’t all Apple Music releases be different than Mastered for iTunes releases, based on the logic that the mastering and streaming are technically different. If the Apple Music release is exactly the same as the Spotify release, but the only difference from the Apple Music and MFiT is the blue badge? I think it’s time to merge all the Mastered for iTunes releases with the other digital releases if the only difference is the blue badge. We can rename the series Mastered for iTunes to Apple Digital Masters and attach to appropriate releases, that have that on iTunes.
I agree to remove that concept completely, too.
In the meantime, I have updated the series aliases, but if you have more precise date than just 2019, please edit. 
Even if it is literally just a marketing difference, what would be the benefit of merging them?
Because, they are the same. Apple doesn’t recognize an Apple Music release to be any different than an iTunes release. They give the same iTunes ID if there is no difference in barcode, label, etc. There are some instances in which the barcode for MFiT is shared with Spotify/Deezer, etc. that are the same as Apple Music as well. Of course, I’m talking about only releases that share all the same information, not those with different barcodes, etc. Most MFiT would be unaffected as most get their own barcodes.
I hope you don’t mind me resurrecting this, but I’d like to know if the distinction between standard and MFiT digital releases should be still made even if they share the same barcode with releases on other platforms (Spotify, Deezer, etc.). I never cared about this too much (kind of assumed that if it’s mastered for Apple/iTunes, then the barcode shouldn’t appear in Spotify and other vendors) and I thought less and less people were concerned about MFiT as a category worth distinguishing, until I saw this edit: Edit #104978863 - Remove relationship
Everything seems to be the same with the instances on Spotify & Deezer down to the UPC, except that the one on Apple seems MFiT as reported by toadking’s script.
Looking at this series, I could spot a few releases with links to other digital vendors too, except I’m not sure if that’s rather due to lazy editing.
No. We no longer keep those separate. The reason is they really aren’t different releases. They are mastered to Apple Digital Masters (now the name for Mastered for iTunes) standards to be able to have that distinction, but the releases that share the barcode are the same master. Just like we don’t separate out FLAC, MP3, etc. or even hi-res from standard now. If the differences are only the master, file type, bit-rate, etc. If all else is the same, they should be treated as the same release. You will still see plenty that haven’t been merged, but many have. There are even releases that are both Apple Digital Masters & Tidal Masters (now called Max). They are all just marketing gimmicks and it mostly relates to how you want to playback the release. We’d have to create so many duplicate releases if we started separating out all the differences like this.