That's not the way I look at Myth's guide. More generally, I don't think that's what a guide is for.

A TW game is so complex in possible permutations and combinations, the idea of "optimal" is elusive. In any case, a player searching for "optimal" is well beyond needing a guide. Instead, what I believe Myth is offering here is a solid, successful way to get through the early turns with Rome and place the faction on solid ground for mid- and late-game. And that's all a guide should be. After all, the folks out there looking for a guide are probably the folks who are finding themselves struggling to get a good start. Or, other players who've had some success with a faction but see some ideas here to improve.

An alternative way to view the situation: Let's suppose that Myth's guide (or any other) IS in fact "optimal", and represents the "best" way to play a faction. Beyond that, perhaps the fun of a campaign might be in seeing how successful one can be in making major departures from the "optimum". Examples "Ok, so that conventional method obviously works well....let's see how Rome does if we build all its armies solely from the Aux Barracks and mercenaries...no legionary troops." Or "Let's see what happens if we really push the slave factor in economy....slave markets in every city, enslave after every battle...can we keep the lid on public order?"