I'm all for Win32, but those odd-shapes and custom skins were the precursors and the normalizing precedent for the current default mentality of "visual identity = branding" that's been killing desktop computing experience for years and is one of the reasons we have to endure reacts, electrons and multitude of half-baked widget libraries that consist of things looking like no particular control but all feature blurry text rendering, flaky accessibility, negative information density and their own special sets of bugs.
Unless you're building a Blender or an Ardour or, I don't know, a trading platform or a game, an individualized GUI should be the last of your priorities.
For your average business app, yes, I agree, however there are a lot of apps I use on my iPad that have essentially moved this "custom skin" UI into elements in a full-screen wrapper and they look and work wonderfully. There are also lots of smart devices that have hyper individualized UIs, modern cars, anything in the audio realm with a screen, plenty of examples.
But yes, you're showing a series of forms to fill out? Use the platform native controls and make it work perfectly.
It's different. Electron apps all look the same without actually making much efforts to make them "personal" -- they just want to release an app ASAP so they chose Electron.
On the other hand, the Win32 era "skins" like they ones used in Video Player and Winamp are very personal -- they have distinct styles. Maybe we don't like the styles, but at least they are trying to make a unique taste.
Electron apps do not have tastes. Unless you count flat design + as little UI as possible as a taste.
Modern operating systems are for servers, for corporations. They are not personal. Linux was for hackers and sysadmins then, not power users, and for servers now. Linux does make a come back for desktop because Windows team makes such a herculean effort to trash its own product. The Win 3.1 - Win XP era are the real "personal" era.