With Rhythm of the Wild, you can give them either a +1/+1 counter or haste, either helping your Dinosaurs scale past your opponents creatures or letting them attack immediately
It's not like you'd be unable to splash or play five-color decks
For players who want to play Cloud, Planet's Champion or Sephiroth, Planet's Heir decks, the Starter Kit is a great choice
Unless you have an absolutely massive grip of cards, you'll usually be milling for seven or eight cards for six mana, which isn't a good rate
Misty Salon showcases how some Rooms can care about how many halves of a Room you have unlocked
All three have strong designs that feel like they could support their own decks with interesting mechanics and are only improved with partner