I never understood how it could be otherwise.

Back when I was learning, I had Timex 2068 Basic and Z80.

Then at technical school, each class had its own programming language.

Followed by CS degree, with loads of programming languages.

First job, TCL, C, C++, JavaScript, C#, Java, SQL dialects.

Every single job afterwards required proficiency in multiple languages, even JVM/.NET (interaction with OS, languages that target those runtimes).