[maximara]

Originally Posted by RedMattis

If assume the NPCs make good use of the GURPS magic system (heck it is similar for D&D!) the world would look a bit unlike what most people expect. Not just curing disease, but mages going around using move-earth and similar spells to build infrastructure. It gets even more outrageous if you have entire races where everyone has Magery 1 f.ex. The TL would skyrocket, and it you just end up having to explain why a 2000 year old dwarven society is still TL3.

That... is fine. I have a fantasy setting where magic is abused by some groups to a high degree. But it is also common for settings like this to have all these amazing powers but no one abuses the utility of the powers like you'd expect. Perhaps the gods don't like it or something. Or maybe it is just a genre assumption.

Actually that is exactly what Equivalent TL (ETL) is designed for.

Equivalent TL is a concept introduced in GURPS Fantasy p. 66 where magic is so common that it is effectively technology in of itself. As such it is a form of Divergent Technology but may not reflect the "actual" TL if you ignore the magic.

"Look at a number of commonly used spells, assign them to approximate TL equivalents, and see if these cluster around one or two TLs as usually defined; if so, use a rough equivalent TL in that range. If that doesn’t work, the TL concept may not fit the setting." It is advised that the GM should avoid assuming the setting will simply be 'just like TLx but with wizards'

And as Magery 0 Magic in Worldbuilding shows even Magery 0 spells can drastically change things. Preserve Food would change so many things in TL3 that odds are it wouldn't be ETL3.