WinForms apps always felt "tight" compared to all the other options (the development experience and the end product), and there were lots of 3rd party controls available. If you were building windows desktop app in the early .NET days it sure seemed like the way to go, and those apps lasting so long looks like a supporting data point.

EDIT: just dug out a "memory magic" winforms app I wrote sometime in the early 2000's and ran it no problem, no weird looking non-native UI or long electron startup...