You can, by construction, create an additive solution that interacts with only your choice of bits of the previous system. To remove, you must be sure you know

You can, by construction, create an additive solution that interacts with only your choice of bits of the previous system. To remove, you must be sure you know the full interaction graph it already has. I encounter this in code all the time. I'm currently dealing with a support case where I tried to remove ~10 lines of code, and wouldn't you know it, it's causing issues. By contrast I add lines of code by the hundreds all the time with virtually no issues. Jenga's only a metaphor, don't too caught up in it. Most human-designed systems don't have dependency graphs that look like that. Ugly ones, sure, ones that don't match the pretty diagrams, sure, but we don't generally build systems where literally everything critically depends on everything else, if for no other reason than we aren't good enough to build that sort of system without it coming down around our ears almost immediately. We have to have some degree of isolation. https://xkcd.com/2347/ https://xkcd.com/2347/ (There are multiple places where for simplicity I'm not adding caveats, like, obviously I can't always add 100s of lines with no issues.)