The thing is, cross-platform tooling sucks. A plain CLI program is already bad enough to get running across platforms - even among Unix/POSIX compliant-ish platforms, which is why autoconf, cmake and a host of other tools exist... but GUI programs? That's orders of magnitude worse to get right. And games manage to blow past that as every platform has their completely own graphics stack.
Electron and friends abstract all that suckiness away from developers and allow management to hire cheap fresh JS coding bootcamp graduates instead of highly capable and paid Qt/Gtk/SDL/whatever consultants.