Interestingly, Excel et al. achieved that status without the "no-code/low-code" mantra that is the rage in sales these days, where "citizen developers" are expected to relish in GUI editors severely limited in the logic they can accomplish.

On a turing-completeness spectrum, they live on the opposite half of where VBA+formulas stand proudly. Therefore, it is no surprise that for anything beyond "out-of-the-box", it is expected that an experienced IT developer/consultant will be needed to figure something out.

A decent reason to disallow custom code is that these platform are to be upgraded regularly, yet every major version seems to bring its lot of breaking changes while my decade-old macros still run like a champ. Oh the irony.