> Now, you change a little thing in your code base, and the only thing the testing suite tells you is that you will be busy the rest of the day rewriting false positive test cases.

Never happened to me, and we use a lot of junit tests at work.

I don't see the value in "Do not isolate code". Isolating a single method or such is often necessary, especially a unit test of a Utils class. But I only tend to do this if the "user story" centric test cases don't end up covering everything.