@mkunikow i feel like this is an oversimplification of both the benefits and costs of unit testing and immediate feedback. I don't think the parent article was dismissing unit tests out of hand; rather, he was elaborating on the hidden costs of unit tests.
You mentioned refactoring. From my perspective, unit tests actively prevent refactoring, if the intention is that a refactoring does not break any existing interfaces. What is helpful in refactoring is to have a set of tests that define the boundary of the refactoring. Its a proactive statement that this is the interface we're protecting, and any client of the interface can be assured that it will not change. Under the covers, all bets are off and in fact a refactoring probably will break unit tests below that functional interface.
Likewise, immediate feedback is not helpful when you are working on code you know is broken, in flux, or incomplete. Its like the proverbial child in the back seat of one's car on a long road trip, incessantly asking "Are we there yet? Are we there yet? Are we there yet?" No, kid, we're not there yet and if you ask me one more time I'm going to pull this car over...
Also, while statically typed languages do protect you from careless or inadvertent typing mistakes, they do nothing to ensure that you've got the business or domain logic correct. BEAM projects have the benefit of dialyzer, which provides most of the benefits of static typing in an accessible package.
All of the above isn't to discount the value of unit tests while developing code, or having a test suite that runs very quickly so as to provide real-time feedback to a developer, on request. I very frequently write tests whose purpose is not to be long-lived. They are there to provide a scaffold to build code around, but they provide no real value in the longer term. Sometimes they're even experimental in nature, when i'm trying to get a feel for how an interface should work. In either case, I try to delete them once I've discovered the true boundaries of the interface and have written tests that define it and cover the edge cases. Of course, this is what i've found works for me, to each his own and YMMV.