I'm not sure about that, for anything besides static resources, given the rate at which various vulnerabilities are found at and how large automated attacks can be, unless you want an up to date WAF in front of everything to be a pre-requisite.
Well, either that or using mTLS or other methods of only letting trusted parties access your resources (which I do for a lot of my homelab), but that's not the most scalable approach.
Back end code does tend to rot a lot, for example, like log4shell showed. Everything was okay one moment and then BOOM, RCEs all over the place the next. I'm all for proven solutions, but I can't exactly escape needing to do everything from OS updates, to language runtime and library updates.
That and a small collection of other things are standards based and not going though changes.
