Tcl was my first "general purpose" programming language (after TI-basic and Matlab).
When I started that job I didn't know the difference between Tcl and TCP. I spent a couple months studying Phillip Greenspuns books. It also made me a better engineer because unlike PHP I couldn't just Google how to do basic web server stuff so I had to learn from first principles. That's how I ended up building my first asset minification pipeline that served the "$file.gz" if it existed with content-encoding: gzip.
Nearly 20 years later and I'm basically a http specialist (well, CDN/Ingress/mesh/proxy/web performance).
Tcl is still kind of neat in a hacky way (no other language I've run across regularly uses upvars so creatively).
Shout-out to ad_proc and aolserver.
AOLServer was the inspiration to the product I worked on, during my first experience working at a dotcom startup.
We had something similar, however it would plug into Apache and IIS, more configurable across several UNIXes and RDMS, and eventually even got an IDE coded in VB, for those folks not wanting to use the Emacs based tooling.
Eventually we also became a victim of the dotcom burst, however many of those ideas were the genesis of OutSytems platform, then rebooted on top of .NET, and still going strong on the market nowadays.