Unfortunately, no one has the time to do that (or let someone do it) after the problem is "solved", so over time the "rebuild from scratch" approach just results in a loss of actual troubleshooting skills and acquired knowledge --- the software equivalent of a "parts swapper" in the physical world.
Unfortunately, no one has the time to do that (or let someone do it) after the problem is "solved", so over time the "rebuild from scratch" approach just results in a loss of actual troubleshooting skills and acquired knowledge --- the software equivalent of a "parts swapper" in the physical world.