I've seen sciter come up in discussion on quite a few threads related to Electron and other web browser embedding systems, but I've never seen a good answer for "why not sciter", so I'll try to put some points out here:
1. Electron is open source, sciter is free as in beer only.
2. Electron implements the exact same javascript as the web, sciter implements its own js-like language. Harder to find developers with experience, and harder move your app from sciter to some other engine down the line.
3. Electron implements the exact same html/css as the web, sciter implements html/css from a few years back plus its own proprietary bolt-ons. Same problems as #2.