Among other things we've done to ourselves, we've got higher-resolution displays, and we have GUI apps that can scale to different resolutions seamlessly. We have support for high DPI displays. We have fonts with sub-pixel rendering for sharper, easier to read text. Speaking of font-rendering, we have Unicode and internationalization support, so that people who read and write Arabic, Chinese, Japanese and other languages that don't use the Latin alphabet can use their native language in file names, dialog boxes and in anywhere else they might want to. We have better support for screen readers for the blind. For people who aren't fully blind, but have vision problems, we have the ability to make text and UI features larger dynamically to support them. We have better multitasking support, including process isolation to keep a badly-behaved application from crashing the entire computer. We have better security at the OS level to prevent malicious applications to take over the whole machine.

That's a big part of what we've done to ourselves. And this makes computers better for a whole lot of people.

Yeah, no.

First, all those things sans high DPI functionality existed in 1998.

Second, most of Electron apps don't benefit from these theoretical advancements.

Preemptive multitasking existed in 1998 and worked every bit as well as it does today. Even in MS Windows.

Security, nah. We have more attack vectors than at any point in the past. And just more crapola caked on to "protect" against those.

How much time and expertise did it take? Did automatically work on all OSs? Could person without tech background slap something like this in a weekend? Did it have accessibility built-in? Could you reuse it on web?

Yes, in 1998 there were full fledged IDEs which allowed for GUI development. Delphi, Visual C++, Visual Basic Powerbuilder, NeXT Objects,.... I would actually say that it was easier to develop apps in 1998 than it is now.

Easier to write? I’m curious are there any sample apps like this that I can read?

Sure. Check out the tutorial that has remained pretty much the same since I used it to learn FLTK + GL 23 years ago:

https://www.fltk.org/doc-1.3/fluid.html

You pretty much draw the UI in fluid and fill out the callbacks. Yeah it's C++ but it's not particularly esoteric C++.