Earlier quoted context omitted.
To expand, it's these 7 lines. (Actually 12) - more or less. Maybe not precisely that, but it's the bit where you add a payment form to your website. It's a nice headline, but it really leaves out the tremendous amount of back-end work that went into making that front end easy to use.
The PayPal form is roughly the same number of lines. The real break through for stripe was it was an alternative to PayPal with a modern UI.
But we switched because PayPal just did not work. A significant percentage of card transactions failed for absolutely no reason, despite "good" customers (school teachers from first world countries), no chargebacks and no fraud. Cards would routinely magically work the next day, and in the end we came to believe PayPal arbitrarily failed card transactions to force people to set up PayPal accounts.
Moving to Stripe resolved this overnight. We'll never go back.