You appear to be trying some sort of reduction ad absurdum, but in many cases work on some change to the software starts with deleting all the related tests bec

You appear to be trying some sort of reduction ad absurdum, but in many cases work on some change to the software starts with deleting all the related tests because they're going to be irrelevant and changing them isn't worth the extra work. That that deletion is necessary means it apparently did make the code a bit worse. Also all the time they were in while the code wasn't being changed, they made running the application's tests slower.