https://www.channelfireball.com/articles/how-many-colored-mana-sources-do-you-need-to-consistently-cast-your-spells-a-guilds-of-ravnica-update/
It depends on what's in your deck, obviously. If you're trying to cast Steel Leaf Champion, then you need at least 23 green sources. That means you won't be able to run 2 colors. But if all your low-mana cards are artifacts and your only colored cards are 5-mana cards that cost only one colored mana, e.g. Kenrith, then you only need 9 white sources i.e. you can get away with 3 color decks.
Thank you, I know this. But this is Standard wisdom. I'm wondering if kitchen table expectations are lower.
I mean, in Limited we also run 2 colors with all basics and it's better than mono color. Though there's also the aspect that you're unlikely to get 23 good cards in the same color.
But think of a card pool where you have mostly commons and uncommons - enough quantity to build a mono colored deck. Do you still go 2-color with all basics or common dual lands?
Then it becomes a card quality question. Do you have any payoffs for staying monocolor? For example, Steel Leaf Champion is a powerful payoff for staying mono G. So are cards like
Vivien, Arkbow Ranger. These cards are strong, but to play them you need to stay mono G. Meanwhile Rekindling Phoenix is a great card that isn't nearly as color intensive. You could conceivably play a mostly-red deck and splash
Blessed Light.
If the best cards in your pool aren't so color intensive, then you should play 2 colors. If they are color intensive, then you should stay monocolor.