Because companies give zero fucks. They will tell you they need tons of IT people, when in reality they want tons of underpaid programmers. They want stuff as fast and cheap as possible. What doesn’t cause immediate trouble is usually good enough. What can be patched up somehow is kept running, even when it only leads you further up the cliff you will fall off eventually.

Management is sometimes completely clueless. They rather hire twice as many people to keep some poorly developed app running, than to invest in a new, better developed app, that requires less maintenance and provides a better user experience. Zero risk tolerance and zero foresight.

It still generates money, you keep it running. Any means are fine.