Nobody has a big enough test set to A/B test every combination of elements for a web page, a product feature set, or even a conference presentation. The combinatorics are just unwieldy.
Someone has to have multiple good ideas and the ability to carry them out properly before an A/B test is even valuable. Otherwise you're measuring one uninformed random change against another. A/B confirms whether you've succeeded in improving something. It can't really suggest what to try next.
Someone has to have multiple good ideas and the ability to carry them out properly before an A/B test is even valuable. Otherwise you're measuring one uninformed random change against another. A/B confirms whether you've succeeded in improving something. It can't really suggest what to try next.