This sort of combinatorical complexity only really exists in theory. The overwhelmingly common case is that FF A and FF B are independent, and can be successful

This sort of combinatorical complexity only really exists in theory. The overwhelmingly common case is that FF A and FF B are independent, and can be successfully tested independently. You test FF A on & off, FF B on & off; your tests grow linearly with your FF set (which you should be pruning as soon as the feature is deployed). Also, since the original comment stated, > often skips integration/e2e testing They're probably responding with the expectation of this being compared to doing no testing at all. Merely assuming your FFs are independent, and testing them as such, is greater than nothing at all, even if the rare correlation might exist. And where a correlation might exist, well, that's what your judgement & expertise is for. Absolutely test that if you find yourself in that case.