Of the failure modes I've had to deal with, even when we did use a lot of interpreted scripts which could be live-patched, very few of the important issues were fixable that way. Because the stuff which broke was
rare and
deep.
One could argue that everything would be config-related if all the code were interpreted and considered to be configuration. So absolutely everything could be fixed in Production.
I'd argue that absolutely everything could be broken in Production too, in that case. The point is that you test the invariant stuff, and have a small surface area of variables which define the permutations of Live behaviours.
Configuration is not code. Code gets tested and doesn't vary between Canary, Nightly, Stable Test, Customer Test and Customer Live for a given build.
Because some of us build stuff for customers who won't justify the 'risk' of updating every day, and have upgrade cycles measured in months.
