Well A/B testing has been around for ages. We did traffic splitting to two variations in the 1990's. No fancy tools, but fundamentally same. In regards to one-l

Well A/B testing has been around for ages. We did traffic splitting to two variations in the 1990's. No fancy tools, but fundamentally same. In regards to one-liners, there probably were multiple changes occurring over long time, interleaved: - Increasing information overload etc changed visitor behavior to prefer less text. - Large companies who did A/B testing eventually noticed that change in visitor's preferences and evolved towards one-liners. - Some small companies who didn't do A/B testing copied the one-liner style from large companies, when seeking "inspiration". - Remaining small companies followed, as one-liners were the dominant trend.