You're not wrong. Personally, I just used GitHub's web UI to preview my PRs, but I suppose having a local GUI makes it easier to amend commits and not have to force push changes.
Electron apps eat my ram and web UIs run like shit when backed by a large private instance.
It was mentioned elsewhere but you might find Sublime Merge to be useful; it's not based on Electron, it's very fast, and it makes working with various git workflows a lot nicer (to me, at least).