Sorry I never used a Mac, but how can undo be a "wonderful" features ???

Undo on native Cocoa apps have a few delightful “smarts” that you begin to take for granted and can be infuriating when absent.

For instance, native undo is time and word sensitive. I don't know its exact heuristics, but it always seems to do what you meant.

Gmail's Chrome and Electron, on the other hand, will often undo letter by letter or leave you in mid typed words, which is nuts.

If you want another example, I often write in multiple languages, something that's beautifully handled for you on native apps. Since Skype changed to Electron, it puts a red underline on every single non english word I type and there is nothing that can be done about it, besides changing the default system language and restarting the app.

There's also CoreText's sharp line width in retina displays no matter which background/foreground color combination you choose, built in dictionary a tap away, etc.

It's just a dreadful experience otherwise, once you get used.

The features mentioned are built into the standard macOS toolkit, which makes them handily available and consistent between applications. I don't think they were listing them for being unique as much as pointing out the feature consistency.