I doubt that claim so much. Every Electron application I've ever used is seriously deficient in many ways. First every app has its own set of UI controls, so right there you loose one of the best things about native Mac apps, consistency. Next I've yet to find a single Electron app that doesn't break some core Mac feature such as copy/paste, system wide spellcheck, system wide dictionary, the emoji picker, system wide settings, scrollable area bounce, zoom, tabs, windows, menus, keyboard shortcuts, drag & drop, screenshots, and so on. Third every electron app consumes way to many system resources and almost all are painfully slow. But, hey I'll give Figma a try and report back.
Figma definitely stands as an example of what you can do with web technologies. Their webassembly and canvas codebase seems to work out really well for user experience. In comparison I tried Sketch the other day (native) and it was reeeeeeally slow.
Figma is still very much geared towards Mac designers, though. Sure, it works on Windows, but it's very frustrating to use it with a scroll-wheel mouse and a full-size keyboard. Most dropdowns have no scroll bar, if there is a scrollbar it's only 4px wide. They expect you to have a touchpad with inertia scrolling to do anything. The numpad also does nothing, since Macbooks no longer have them (so CTRL-NUM0 CTRL-NUM1 - extremely shortcuts to reset zoom/fit to page - do nothing; you have to use the number keys above the characters).