Not sure where you are going with this story. Do you mean that tests are useless, because you once worked in a company that thought that a large, test-less codebase was a good idea?
No, because I have worked with several dozen code bases, hundreds if not thousands of bugs, and Unit Tests are if anything a bad sign associated with code in desperate need of refactoring. They are the uncanny valley of quality.
Ed: Unit Tests become more valuable as code quality decreases.
Hmm... You're capitalizing "Unit Tests" like there's a need to distinguish the difference between those and what I infer is "code that was not Unit Tests that we ran to verify correctness". Am I correct? Are you drawing a distinction? Or did you truly have no code used to verify correctness? Or no automated way to test?
There are many types of tests, Integration tests are different than Unit Tests. Having a script click on UI elements is fundamentally different from isolating a function to verify it does what it should.
Hint: anecdotal fallacy