Atom was developed before the acquisition. Which brings us to the second proud tradition of the tech titans, acquiring companies to end the products the acquirer doesn't like.
Well yeah, if you have two very similar products (editors/IDEs based on web technology), one of them much more successful than the other, putting a lot of effort into the less-used product sounds a bit hard to justify...
If you look at the contribution activity it dropped off after acquisition of GitHub by Microsoft and it seems that development was redirected to VSCode.
The writing was on the wall for a long while now, and was one of the reasons why the JuliaCommunity stopped advocating Juno/Atom as a platform and instead switched to VSCode
Probably a bit of both if I was to hazard a guess. MS has VS Code, which is definitely the elephant in the room as far as go to IDEs in the environments I’ve been in lately. So right now they’re spending engineering time on both VS Code and Atom, so they may as well focus their resources on the more popular one.
Look at the Atom repo, very few commits in the last year, and it's not like there are loads of open pull requests (serious PRs do get merged), and it's been strongly dropping off for a long time. It's the programming community that abandoned Atom, not Microsoft.
it was dead already, or at least, shown inferior to vscode in feature set. If anything you can accuse MS, it's using its market position and the VS brand name to "steal" adoption, but that completed before the aquisition too.