They're a YC company so every other YC company is going to use them, that's how YC companies operate.
This isn't at all how YC companies operate (source: I did YC), but also... Plaid is not YC.
Plaid has an option to let the client/provider accept plain account + routing numbers, a lot of apps for whatever purpose don't use it.
Plaid is not a YC company
This isn't at all how YC companies operate (source: I did YC), but also... Plaid is not YC.