Why use the GWP formula?

Answer 1

I understand that the GWP formula is used to calculate the warming potential of an atmospheric gas. But when comparing water vapor to CO2, the greater impact of CO2 largely hinges on the time frame CO2 would theoretically remain in the atmosphere. While water vapor may only remain for a couple of days, CO2 has the potential to stay in the atmosphere for 20-100 years. But regardless of time frame, water vapor constitutes and exponentially higher percentage of the atmosphere. So even even if rain falls, since global evaporation and condensation occur at an equal rate, there will always be a gargantuan amount of it. The amount of CO2 in the air has little to no effect on warming, including all natural sources of it. (natural sources of CO2 are over 20 times greater than human-related emissions.) In fact, CO2 has been proven to be a positive feedback of global warming, rather than a precursor or cause. So my question is actually, why use this formula that is actually misleading in terms of CO2 impact on the warming of the earth? Wouldn't it be better if media spokespeople actually discussed each individual gases' abundance, composition of the atmosphere, location in the atmosphere, heat-trapping efficiency and impact on global temperatures?