The cases I have in mind are not because of NIH or because of greybeards' passed-down wisdom from the time when computers had to be carved out of stone. There

The cases I have in mind are not because of NIH or because of greybeards' passed-down wisdom from the time when computers had to be carved out of stone. There are places where there are heightened security requirements (for various reasons[1]). Disallowing unnecessary outbound connections is a standard practice. This results in pruning quite a lot of possible attack vectors. [1] Of course some of those reasons are ridiculous. One place disallowed saving word documents as blobs in an Oracle database running on a Solaris server due to fear of malicious word document macros running on said server.