Every <insert any language here> code base I have worked on, that wasnt written by small team of experts, turned into a huge pile of crap…

:-)

well aligned scala teams are a great thing, impenetrable code is not - maybe a poor choice of adjective?

A lot of work has been done in Scala 3 to simplify everything.

And with the arrival of virtual threads in the JVM there are new concurrency libraries e.g. Ox [1] and Gears [2] which remove the need to use FP concepts like monads. Which have been the major source of much of the complexity.

For all its problems it is a seriously under-rated platform especially Scala.js which IMHO is far better and simpler than Typescript.

[1] https://github.com/softwaremill/ox

[2] https://github.com/lampepfl/gears

You're going to have that problem with any codebase written by people who don't particularly know the language. Typescript written by PHP programmers, Python written by Java programmers, you'll quickly get a huge impenetrable pile of crap.

You can optimize your codebase to be modified by an ever rotating group of people who don't fully understand it, or by a smaller group of people who do. Both are legitimate choices in specific contexts. But if you take a codebase written one way and try to maintain it the other way, your productivity will tank.

I feel the same about Javascript codebases. As I like to say, hell is other people's Javascript.