Scout is better when you're playing only with Intrigue cards. Six of the 24 other cards in Intrigue make Scout a potentially viable option: Wishing Well, Baron, the 3 hybrid VP cards, and Duke (because you green earlier and more often in Duke games). There are only two other cards in all of Dominion that potentially combo with Scout: Mystic and Crossroads. But if you're greening enough to make Crossroads' draw reliable, you're probably greening to early, and Cartographer and maybe even Navigator, Ironmonger, and Vagrant work just as well or better for Mystic than Scout does.
But when playing with all sets, the other Scout variants are usually more useful. Navigator and Duchess work with Treasure-less engines, Cartographer can discard, and the cantrip Scout-variants (Pearl Diver, Vagrant, Spy, and Ironmonger) are more spammable than Scout is, because they don't reduce your handsize when they don't hit VP.
Coppersmith at least fills a unique niche. Talisman and Nomad Camp are useful because sometimes you are willing to pay $4 for a Workshop or Woodcutter. Thief and its variants scale with multiplayer.
Perhaps the most damning argument against Scout, however, is that the only non-vanilla Ruin is a Scout variant. That gives you a good idea of what DXV thinks of Scout's "power".
Scout does have one good use--in slogs, late in the game when you don't have $5, it can be worth picking up a Scout to move through your deck faster. But in that respect, the oft-mocked Chancellor, with its coins, is probably more useful than Scout is.
