> Compare it to Linux UIs where you often have to grab a single pixel border on a 4k monitor to resize a window.
On Linux you hold the super/windows key and click/drag anywhere on the window to move it, or right-click/drag anywhere on the window to resize it. It's much easier than using thick borders. Discoverability is admittedly not great, but this feature easily coexists with window borders. Microsoft could keep the thick borders by default and also implement this.
“Don’t do it the way everyone else does it or the way you’ve always done it; our designer decided to make that hard for <inscrutable reasons not related to delighting existing users> and instead we offer this hard-to-discover non-idiomatic workaround.
“You will grow to love the workaround because it doesn’t hurt nearly as much, kind of like stopping after you’ve been hitting yourself in the head with a hammer.”
I guess you (deliberately) missed the part where the two features coexist perfectly fine. There is no "“Don’t do it the way everyone else does it", you pulled that out of your ass. All the Linux DEs worth mentioning have draggable window borders that are familiar to any Windows or MacOS user. The default width of those borders varies, but thick borders by default are common.
On Linux you hold the super/windows key and click/drag anywhere on the window to move it, or right-click/drag anywhere on the window to resize it. It's much easier than using thick borders. Discoverability is admittedly not great, but this feature easily coexists with window borders. Microsoft could keep the thick borders by default and also implement this.