It isn't the telemetry that's slowing us down, but layers upon layers of (mostly needless) abstraction and buffer bloat.

Windows 95 had most of the things we use in a GUI environment today and it ran on a 486 with 8MB of ram. When packaged in Electron with a javascript x86 emulator it is still smaller than many modern text editors. Plenty of GUIs ran on significantly less.

Since the modern web is basically one of the worlds most overengineered and crufty VM platforms, I don't expect it would run very well, and that would probably be enough to doom the system in the eyes of many, sadly.