I use them because they look nice and with an OLED I wanted a dynamic wallpaper so I wouldn’t get screen burn in. There is adult stuff but everything I use is just video games and matrix scrolling patterns, that kind of stuff, so I can tell my monitor is on without getting burn in. I’ve got a high end desktop so can take the minor performance hit running it all the time.
Unfortunately seems like I’m going to be uninstalling it.
The 'wallpapers' in question are pirated games made in renpy (python game engine) or rpgmaker (js based), which makes them a really good vector for malware. As another commenter noted this is a bizarrely common way for Chinese people to get porn through the great firewall.