There is a fundamental difference between drawing boundaries to protect incumbents and using competitiveness as a factor among others to draw maps.
There are arguably two, but one fundamental difference lies in the "a factor among others" bit.
The "in november" part is quite relevant here. A district representing a community of interest, or a number of readily definable non-divided smaller communities of interest, is much more liable to throw up a primary challenge if the incumbent becomes unpopular.