Looking at the responses, its mainly because of the age of the technology and its capabilities when compared to todays best practices.

Could the decision to not recommend for production fall within the scope of the known CVEs?

I understand the usability in IRIS, but InterSystems specifically states "CSP is not recommended for use in new applications" Why? Any further discussion of CSP in that document doesn't support that statement.

Is it as @Dmitry Maslennikov mentioned above, that it's because of the age of the framework vs SPA's or reactive technologies that are in the open source community now? Is it due to security and protection of the data? I'm sure I could come up with a hundred different answers, but if the Company's product isnt recommended in new applications, an explanation of why should provide clients the necessary justification to either stay with CSP or move to a new frontend platform.