It's not about being afraid of computer science, it's about being pragmatic and efficient about the problems that you choose to solve. By choosing to develop your own closed-source language, you now have two projects that need to be developed, the product itself and the language that it depends on. They retired the language (Wasabi) some years later specifically because it was so demanding to maintain, there was significant on-boarding for any new hires, and it constrained their developers by frequently being behind the current state of C# (which it compiled to). When you write your own language, you don't have an entire open source community updating it, fixing bugs, and maturing it with new features and libraries. That is now work that your team needs to take on, and in the vast majority of cases, the negatives far outweigh the positives.