These projects quickly reach a point where evolving it further is too costly and risky. To the point that the org owning it will choose to stop development to do a re-implementation which, despite being a very costly and risky endeavor, ends up being a the better choice.

This is a very costly way of developing software.

It's easy to say that organizations should do it right the first time, in terms of applying proper engineering practices. But they often didn't have the time, capital, and skillset to do that. Not ideal, but that's often how things work in the real world and it will never change.