I'm curious why you see TCL as a "competitor" to Forth?
The entire Python default windowing system relies on TCL, and companies like AMD use it for a lot of their internal test frameworks because it's easy to implement and well supported. So for embedded, which is people's argument for fourth, TCL is way more useful as evidenced by it winning the industry.
... the argument for Forth embedded is usually Forth directly on hardware, not "embedded into another app" like TCL?
Does TCL has a purpose since Forth exists? Serious question.
TCL being stringly typed makes it dead on arrival for me, and I'm sure others feel the same.
Extremely widespread embedded support and cross platform. Forth seems dead to me, whereas TCL is huge and has good docs, a good standard library with batteries included, and it's easy to implement on embedded hardware because of how well documented it is. Also the inherent linkage to Python keeps it relevant.