I think that one of the things that this rule was meant to avoid is questions that are primarily opinion-based. Many of these primarily opinion-based are asking something like "What is the best (practice) and why?". Considering that there is a separate close reason for "primarily opinion-based", the on-topic rule about "best practice" doesn't apply much here either.
My vote is: Remove the rule for now. If question quality drastically decreases, then consider re-adding a clarified version of the rule.