TADS does have a significant amount of learning material, actually similar to Inform 7.
TADS: Quick Start, Getting Started, Learning, Tour Guide, System Manual, Tech Reference, Library Reference, Into to HTML TADS. Adv3Lite: Library Ref, Manual, Tutorial and example source code. (Most of them 100s of pages long - Written by Eric Eve) That is just the references included in the source code - others available on the internet.
The learning curve is initially steeper than I7 but is a much more detail rich world model is available. Adv3lite is SOMEWHAT similar to I7 with its constructs. Some (me included) feel that I7 becomes more difficult as you implement actions that are less than basic. Adv3Lite is not a watered down version of Adv3 includes a feature set that are the most commonly used. It well worth consideration.
I am looking at hosting a Winter TADS Jam that would take place well after IF Comp. I will publish the details shortly. Maybe there would be some interest. (Nov. 14 - Jan 15 entry period followed by judging via itch.io)
I enjoy TADS and don’t want to see it fall into obscurity!
Thaumistry by Bob Bates is a great example of what can be done with modern TADS.