The Maxwell-Boltzmann distribution is a continuous probability distribution of continuous variables, so it has both a probability density function and a cumulative distribution function where the latter is just an integral over the former.
I guess I'm wondering then why the Maxwell-Boltzmann distribution doesn't just take the general form of the cumulative distribution function (the derivative of which is the probability mass function) with appropriate constants.
I don't follow any derivations of the maxwell-boltzmann distribution I've found (I probably should work harder to understand), and when I tried to derive it myself I got the cumulative distribution function. The problem with this is (a) it's somehow different than the maxwell-boltzmann distribution, and (b) I have no idea how to evaluate it.