Everyone knows github. Adding microsoft to the name doesnt get more sign ups. Npm doesnt even get sign ups this way. I have no idea what Revue is. Adding Twitter to the name gives it instant credibility.
Microsoft wants to keep their corporate stink off of those brands as to not taint their market dominance and continued growth. It appears to be working.
They're slowly working other, less-Microsoft-branded proprietary stuff into them, like Azure and VSCode.
GitHub and NPM however remain without even a mention of their ownership and decisionmaking entity.
Some of the marketing for these things they've even taken to posting on unaffiliated domains, like we saw on HN yesterday:
They're trying really hard to not remind people that the same people who put ads in your start menu also own and control your favorite free code host, too.