There is an xiosia quest, that is repeatable for the xiosia faction for example, i know this as im guilty of doing it several times XD
If quests were to be based on factions instead of a chain, sombody could do said quest over and over and over again, getting mabey 200 xiosia points, thus allowing them to skip any rinky dinky small/medium quests with little to no reward and go straight to the final badass quest for some glyph.
I doubt the devs would want that, that either making them not repeatable, or making the quests both chain 'and' faction based, would be the plausable choice