I think the article misses the point that many design modifications are micro-optimizations. The entire goal is that the user doesn't notice (cognitively) but is modified in their behavior none the less. These sorts of micro-optimizations frequently made Travelocity hundreds of thousands of dollars when I was their A/B test developer. Adding a phone number to one page added an estimated $3 million in revenue.
Adding a phone number is good, yes if it adds $3 million dollars, go ahead and do it!