I haven't played a lot of Tyranobuilder games, but in general it just seems much less user-friendly than Ren'Py. The Fate of Irnia, for example, doesn't actually let you quit because the dev forgot to include a quit function- you have to alt-tab out and use the taskbar to manually close it. It also doesn't use a universal save location, so it's much less convenient for games where you have to download multiple updated iterations, since you have to copy the saves across by hand to avoid having to start over with each new patch version.