For one thing, the mechanic has a ton of different options, and getting players to venture three or four times every turn would not only melt their brains but also take away the feeling of progress that's so much fun in going slowly
Yeah, you might need to, if you have actual zero Dredge cards in your hand, but even Street Wraith and Gitaxian Probe make a good case for keeping and hoping
The armored construct seen in Painter's Servant stands in a sunny mythical city, glistening in the daylight
It puts the card directly into your hand, which circumvents drawing restrictions such as Notion Thief and Narset, Parter of Veils - and with that also doesnt count towards other catch up cards like the Smugglers Share mentioned earlier
Honestly, even without Dryad Arbor, Im a little afraid of it in Devoted Druid combo decks, but at least Im only really worried about it there and not also in Infect, G/W Hexproof, Primeval Titan strategies, any Tarmogoyf deck, etc etc