Not sure where you read that. Both articles don't seem to say that. The Apple one says "Apple Music is not a backup service" (which iTunes Match is)... and the other one says that iTunes Match uses a better algorithm to match and is a backup service. So, yes... iTunes Match still has a purpose... mostly for all those songs which are not available in the iTunes Music Store / Apple Music and need to be uploaded
EDIT: I just saw it later in the article. Yeah, this isn't fully true. If you have uploaded tracks in your iCloud account from iTunes Match, you won't be able to download them on your iOS / iPadOS device (unless they changed this... no idea since I still subscribe to iTunes Match)... Every time I tried to download my library to my device in offline format, it always threw errors on Uploaded cloud items but once I renewed iTunes Match, it stopped doing it. Also keep in mind that Apple themselves said Apple Music isn't a cloud service... they would knowthat would seem to reason that anything Uploaded wouldn't be in the cloud for you except MAYBE to stream.
No, is not. It hasn´t the ability to force the upload of a particular track, so if for example the algorithm matches a remastered version of a song with the original version (or viceversa), there is nothing you can do to correct that.
Subscribe to iTunes Match - Apple Support
iTunes Match gives you access to all of your music on all of your devices, even songs that you've imported from other sources such as CDs.
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iTunes Match isn't a back up service, so make sure to always have a back up of your music collection before you make any changes.
As for your edit, never happened to me. Uploaded music always downloaded and played fine in my Apple devices even with just the Apple Music subscription.