I don't really get why the positive test rate is not supposed to have gone up significantly with availability of at home tests. Shortages of at home tests would

I don't really get why the positive test rate is not supposed to have gone up significantly with availability of at home tests. Shortages of at home tests would naturally lower it again, but isn't this a useless number now that we don't know how many people used tests they already had at home to skip being in the negative reported results?