Less painful according to who? From reading this thread it appears that most devs claiming it's incredibly easy have never actually worked with other UI toolkits at all, so their experience is largely worthless.

I've done web UI dev. I've also written code using GTK, Qt, Windows, Swing and JavaFX. A good modern UI toolkit like JavaFX or Qt blows the web stack out of the water on almost every metric. Developer productivity, correctness, speed ... you name it.