So their reasoning is that they are not getting the productivity they want but how can they even measure that to begin with?
There's way too many factors at play including the individual developer and how much experience they have relative to the project and feature/bug they are working on.
As a developer, I love learning about a new tool, language feature, etc and applying it to a software system which a lot of the time comes from reading documentation or an article on the topic. This is absolutely needed to grow in one's field especially one that changes as much as IT.
Keep up with modern trends is critical for the scalability of a company as old code can cause leaks and vulnerabilities in your system; if the developers are constantly writing code for the company's own system, how will they will ever know the latest innovations in other systems by other developers?
One thing I like to do is search a topic in Google and select "this year" to filter out all the latest articles on research or practical topics. For example, my last search like this was about writing secure software with typescript to get what people are really talking about.