A) Create separate apps for each platform B) Make one app that can run on all platforms with minimal changes
Electron is a very popular way to build a webapp and make it look like a real "native" app. It is great in concepts: companies can build one app, and they only have to make minor changes between platforms.
In practice, Electron apps hog a lot of memory and can appear slow. Electron is basically a web browser rendering a web page. When you have your regular web browser running, along with a handful of Electron apps, you're really running several comletely separate web browsers all at once. On top of that, Electron is built off of Chrome, and Chrome is a huge memory hog.
So, companies that create Electron apps go that route to save time and resources, hogging up users' resources. For 1Password, it's supposed to be a tiny app the mostly just lives in your OS's menubar or taskbar with a minimal UI until you need to open up the larger window. Instead, there's a whole instance of Chrome soaking up memory in the background while your app is idle.