I have no horse in this argument, but I'm interested in the mathematics of it.
I don't think it's fair to say "everyone gets 5 ABs" and extrapolate the numbers from there. If a team is batting .700 as a whole, they will get more ABs than a team batting .600 as a whole. Instead, the best way I've determined so far is to look at out generation. A .700 team generates 3 outs per ten at bats. A .600 generates 4 outs per ten at bats. We can then look at total outs per game and how long it would take each team to generate a complete game's worth of outs. I also think it helps to look at this in fractions.
Assuming a 7 inning game (21 outs), a .700 hitting team gets a hit 7/10 times and makes an out 3/10 times. Across 21 outs, it takes 7 trips through the lineup to generate 21 outs. 7 trips x 10 batters = 70ABs. 70ABs x.7 = 49 hits per game.
Doing the same with a .600 hitting team, we get 6/10 and 4/10. Across 21 outs, this team gets 52.5ABs and generates 31.5 hits.
In the middle of putting this together, I see that EdFred came to similar conclusions as I did.
Where in my argument of slugging percentage did I ever say a person had to hit a HR every single time at bat?
At a 4-HR limit, you will score exactly 4 runs every time. How realistic is that?
Like I said, how many of those extra runners are you leaving on base because your averaging singles at .700 instead doubles at .600? How about my power-hitting team hitting their 4 HRs and not committing any DBOs? Their triples and doubles will leave less men stranded for the same number of outs.
Even if you want to add errors and speed of the runner and all that other white noise to the equation, add it to both sides if you're going to be fair.
The math set is done assuming one team only hits doubles and the other team only hits singles. All other skills (really just base running) are equal. Things like errors, advancing on throws, triples, HRs, etc. aren't factored in. If I wasn't at work, I could probably work in a triples and HRs factor given certain rates, but I don't know that it would actually make that big of a difference.