The thing is that most people don't understand that the code needs to be tested anyway. If you don't test it, you are just an idiot who has no proof that the code does what it claims to do. Now because you have to test it anyway, you can just simply spend the same time writing a unit test instead of executing the code with manually configured non-repeatable test cycles, a.k.a clicking through the UI, or sending Postm…
To add to this sentiment, tests also give teams confidence that is needed. It gives engineers confidence when developing new features because the test suite will break if you introduce a regression. It gives engineers confidence during deployment/CD. While the tangible benefits of unit tests are very important, there are other intangible benefits that are equally important.
The confusion here between unit testing and automated testing in general kind of illustrates the author’s point: we’ve become so obsessively focused on one kind of testing that we aren’t thinking critically about its alternatives (of which there are many others besides “no tests”).