This is likely true for many companies. However, it is also a metric for what type of working environment it will be. I value being able to learn quickly and creativity over pre-training.
The article doesn't understand programmers. People will stay because they are passionate about OCaml and there are not a lot of OCaml jobs.
When hiring for a permanent position, I have the expectation that a programmer can learn a new language and environment. An OCaml programmer for a position that is python or C would be looked on very favorably. Far more attention-getting than “full-stack programmer”.
Hard rules are the problem. There is a lot of "it depends."
After over 40 years of programming, I continue to reduce the size of functions and find it easier to write and understand when I return to them. Ten lines are now a personal guideline.
However, a linear function with only tiny loops or conditionals can be easily understood when hundreds of lines are long, but not so much with nested conditionals and loops, where there is natural decomposition into functions.
I observed that the same guidelines became rules problems when test coverage became popular. They soon became metrics rather than tools to think about code and tests. People became reluctant to add sanity check code for things that could should never happen because it brought down code coverage.