You thought wrong.
There have always been other variables to consider, but CO2 is the most significant.
You look out at your front yard and you notice that it's getting brown and dry. You also note that there are some weeds starting to creep over from the neighbors. While pulling a few you notice that weeds aren't the only thing coming over as you find several chinch bugs.
So, should you hold off on watering the lawn till you've pulled the weeds and treated it for chinch bugs? Would that be the SMART thing to do?