"because it's easier"
I'm disappointed by the article. Thought it was going to detail how Electron is actually a good choice, not how they had two separate teams for the different platforms and wanted to get rid of doubly-implementing features (not wanting double work is the obvious requirement and leading reason for going Electron).
I mean, git itself is cross-platform and not Electron. How more obvious does it need to get? It even has a GUI. Telegram Desktop is a modern example that did it. And Libreoffice. And Firefox and Thunderbird. And Audacity. And FileZilla. And everything else traditionally written in the open source community.
Java applications aren't great either. Due to their platform-independentness things like selecting and context menus seem to be re-implemented by every platform ifnot every project, leading to a lot of inconsistency and ugliness. But at least they aren't as sluggish as the web crap dubbed into being native that Electron is.
There are lots of good options but all the engineering blog is able to give for a reason is that it was the easiest.