Why play 3.5 anymore?

[Segev]

It's not explicitly stated, but is made that way by capping PC stats at 20, making AC incredibly hard to increase, as well as removing basically all permanent bonuses to things outside of the normal formula.

So putting a dragon's AC at the extreme limit of "hittable" for PCs would, in fact, make it out of reach for peasants, I think, then.

If the peasants have attack bonuses of +2 or +3, an AC of 22 or 23 is enough to be out of their reach barring the nat 20 that always hits (even in 3.5).