That’s an old argument that goes way back into the early 2000s. Lots of people frustrated with test driven development said all we really need are acceptance tests. The problem with that is that acceptance tests and integration tests leave an awful lot of the code uncovered. And uncovered code can go in any direction that remains unchecked.

The bloat argument is a red herring. The production code doesn’t bloat. The test code is the vice that keeps the production code stable. And those tests are cheap.