We get about 2x mailers per week from AMEX alone offering business loans of up to $500k, not to mention the many other offers we get less frequently.
I like Stripe and think the offer a great product, but I don't think they're doing this because no-one else will.
Even this specific type of loan, called a "Merchant Chash Advance" - exists, and isn't anything new: https://www.fundera.com/business-loans/merchant-cash-advance