Why don't Stripe customers shift to Alipay? I don't know anything about the service, but that seems like a pretty straightforward win, if they're as similar as you suggest.
The key part of the parent comment was 'local payment systems' - that rate is for Alipay payments from China-issued payment instruments, it's not for accepting Visa or Mastercard. It wouldn't be enough for Stripe customers (merchants) to switch to a cheaper payment system, the actual consumers would have to do it as well.
Because countries where both work are not completely overlapping. It'd be very interesting to compare Stripe market share in countries where there are strong competitors.