given that sliced_lemon is one of the lead developers at Mojang, odds are that his views are official for Mojang.
Mojang is a subsidiary of Microsoft. This means that, while Mojang's views might not represent Microsoft's, at least in theory Microsoft doesn't oppose Mojang's views.
The letter is all polite and professional, but at the end of the day it boils down to "we at Mojang won't give a fuck about this place any more.
Apparently Jeb and DB stopped using Reddit a long time ago? I couldn't find recent comments there.
Their feedback site is a mess, so I can get why people would be discouraged from using it. But frankly I'm glad to see even corporate leaving Reddit.
Wow, the minecraft community was huge on reddit. I'm really sad to see it get dispersed. Also I really don't think discord is a good alternative. Let's hope the community finds a great new home..