Atom was just to slow and clunky. The idea was great — see VSCode. But at the time, while being able to hack your own editor was nice, the performance issues and lag was the reason I never used it long term. And pretty much the only reason I ever heard from others.
This was my experience too, and at the time I had been using Sublime Text for years, so Atom was shockingly slow in comparison.
Somehow VSCode does not suffer from most of the performance issues I had with Atom.
Because Microsoft bought GitHub (developers of Atom) and shifted all resources to VSCode.
VS Code already dwarfed it in popularity before MS bought GitHub. Mostly due to Atom being slower, I think.
This analysis might seem simplistic to some, but IMO the reason why the Atom text editor failed is because it was built with Electron.
Vscode is also built on electron though, is it not?
I tried Atom, but preferred Brackets instead. I sometimes use VSCodium too. Previously I used Notepad++ and for quick and dirty hacks, Notepad2