To run a test that asks an important question, that uses a large enough sample size to come to a reliable conclusion, and that can do so amidst a minefield of different ways to be lead astray, takes a lot of resources.

You have to design the test, implement the technology, and come up with the various options. If you’re running a lean organization, there are few cases where this is worth the effort.

Why create a half-assed “A” and a half-assed “B,” when you could just make a full-assed “A?”