This article is implicitly also an example of Hotelling's Law [0]
Essentially, it's rational for firms to move towards "the middle" of the market. That could be the middle of a boardwalk if you are a hot dog stand or the middle of the political spectrum if you are a politician.
It's not necessarily because of testing but rather because being in the middle gives you access to the largest section of the market.
As a counter point, you could argue that a counterpoint is the expression "there are riches in the niches".