I did a fairly high-powered campaign (see campaign log for Against the Idol of the Sun in my signature) 13-20. One of my players called it a superhero campaign. A hasted kensei with a double-range longbow and sharpshooter can snipe enemies from 1200' away. The Warlock used Wish to cast Antipathy on the avatar of a god to shatter the cohesion of his army during the final battle; the party also brought a kraken along, and resurrected a god via an artifact sword the paladin used in what was basically a 1v1 duel versus the CR 28-ish avatar.
It worked. Came close to a TPK because the monk wouldn't use Empty Body, but it worked.