In the old days......
.... unofficial heat swapping e.g., swapping the "A" team and the "B" team's heats, was common and expected race day strategy. Everyone was aware of it even if they chose not to partake of it.
Get rid of the rule and make everyone's life simpler, and eliminate one more ridiculous excuse to DQ teams on "gotcha" technicalities.
"I love the smell of solvents in the morning -- they smell like... victory."