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.