Uncommon bouncelands, uncommon mana rocks, and two common rainbow lands make it possible to stretch your manabase to take on cross-color synergies (like Temur Defenders, Abzan Counters, or Jeskai Prowess) or splash powerful rares
With the latest set, Modern Horizons 2, fully revealed, it seems like this design goal is now starting to come to fruition, with white getting a fair few cards that will improve its position in the color pie dramatically
Of course, this damage output assumes that commanders aren't on the battlefield, and considering how readily accessible commanders are in the namesake format, it's more reasonable to assume that Crimson Honor Guard won't be pushing out its maximum damage potential each turn
This list is also based on my brewing interests, which are interactive decks with creatures (so mostly midrange with the occasional interactive combo deck)