Earlier quoted context omitted.
I feel like that example is missing some context - if signups did increase then their experiment was successful - we aren’t here to make pretty pages, we’re here to make money.
The problem is that it's easy to prove that signups are increasing, and lot harder to prove that there was a measurable increase in number of paying users. Most A/B tests focus on the former, very few on the latter. We had a free plan, and most users who signed up never made a single API request. So, assuming that the increase in signups is driving more business is just foolhardy.
Okay? The A/B test sought to measure which of two options A and B led to more signups.
> So, assuming that the increase in signups is driving more business is just foolhardy.
Your "A/B test enthusiast" was not testing for or trying to prove a causal relationship between increased signups and more business.
If he made the claim separately, then that is the context that is missing from now multiple comments.