I get why someone would want to use it on XBO given that it's a rather closed system, but why would anyone want to use an UWP app over a proper program on PC?
Easy to locate, (re)download, (re)install, and use.
I've had Torrex Pro for maybe 3-4 years now and it's met all my needs across PC/Phone/XB.
I can't speak for you, but that's why I use this particular UWP app over a proper program on PC. I'm sure someone can point to other better torrent clients they prefer but it comes down to personal preference.