Those properties come by definition. Addresses don't change because you can't (realistically) change things any much and move things around.
Basically, think of it like this: you have an old book, written in some magic runes and is told that a certain (quite short) paragraph is wrong and can be badly misinterpreted due to poor wording. You know, the magic spell goes kaboom.
You have tools that can easily and painlessly: a) translate the runes into a text that mere mortal can reasonably easily read; b) scrub runes off the page and write any new ones over; c) translate your text into runes. There is a simple correspondence between text length and how many runes it would take. Now, all you need is to write the new text that must be no longer than old one was. Not a trivial task, but not something extraordinary. Just rare, because we don't deal with magic runes those days as familiars take orders and handle all the gory details.
Writing assembly requires a skill. So does reading old assembly code of a particular function and figuring out what it did. That's admirable, but not something unbelievable.
It's just rarer to see those days, but not a lost art or anything like that. Crackmes are still alive. On the game cheat forums such patching (albeit, for a different purposes) was the norm, and probably still is for the games that aren't protected. And many embedded developers have their fights for code size quite often.
Basically, think of it like this: you have an old book, written in some magic runes and is told that a certain (quite short) paragraph is wrong and can be badly misinterpreted due to poor wording. You know, the magic spell goes kaboom.
You have tools that can easily and painlessly: a) translate the runes into a text that mere mortal can reasonably easily read; b) scrub runes off the page and write any new ones over; c) translate your text into runes. There is a simple correspondence between text length and how many runes it would take. Now, all you need is to write the new text that must be no longer than old one was. Not a trivial task, but not something extraordinary. Just rare, because we don't deal with magic runes those days as familiars take orders and handle all the gory details.
Writing assembly requires a skill. So does reading old assembly code of a particular function and figuring out what it did. That's admirable, but not something unbelievable.
It's just rarer to see those days, but not a lost art or anything like that. Crackmes are still alive. On the game cheat forums such patching (albeit, for a different purposes) was the norm, and probably still is for the games that aren't protected. And many embedded developers have their fights for code size quite often.