Let's take an extreme example. you are facing 65 1 hp creatures.

One person does 65 points of damage in a swing.

The other person does 65 1 point damage attacks.

What you are telling us is that we can derive nothing from showing that on any given hit the 65 damage person will have 64 points of overkill and that his average damage per attack will be 1 x hit chance (which is exactly what my calculations would show).And that we'd learn nothing by showing that the 65 1 point attack person would have 0 overkill and his average damage would be 65 x hit chance (which is exactly what my calculations would show).

Another example:

A character who does 40 points of damage per attack is fighting something with 93 hp. It will always, always, always take 3 hits to kill the target. Always. This means his effective average damage per hit is 31. (specifically, it's always 40, 40, 13). He does 93 points of damage and 27 points of overkill. Always.

Another person does 16 points of damage per attack and is fighting the same creature. It will always, always, always take 6 hits to kill the target. This means the effective average damage per hit is 15.5. He does 96 points of damage and 3 points of overkill.

What you are telling us is that knowing this is completely meaningless. Which is false.

Also, I'm not calculating DPR. None of my numbers are DPR. They are all damage per attack. The numbers don't care how many attacks you have per round. So I have no idea what your complaint is about.

My numbers do, in fact, attempt to take account the variable HP of the target by giving the target a random HP between 1 and its maximum HP. Sure, it's very unlikely a foe will have only one HP less than its maximum when you strike it but it's not completely unreasonable.

Here's another example of why blindly looking at DPR like you propose is absurd. You took GWM as a variant human at level one. You are fighting goblins who don't have a shield because, I don't know, they were using a bow. Using DPR shows that using -5/+10 does 8.95 DPR and not using it does 7.79. So what you're saying is that using GWM is the right way to go. You'd be so, so, so, so wrong.

Using GWM you'll automatically kill a 7 HP goblin just by hitting it. But you'll only hit 40% of the time so, using my calculations (and making the goblin's HP non-random. It's always 7 in this calculation) you get average DPS of 2.80. Which is exactly what you'd expect by trivially multiplying 7x.40. This indicates my calculations have some merit.

If you don't use GWM you hit 65% of the time and when you do hit you'll do 7 damage over 99% of the time. The average modified damage is 4.54 and you'll kill the goblin, like, 64.5% of the time. What you are telling us is that DPR is a better judge of whether you'll kill a goblin than my calculations are. Even though it's blindingly obvious that modified damage and having the ability to know the possibility of doing X damage on any given attack.