It is a Homeaway requirement.
Slightly longer answer
Although Homeaway take payments on your behalf when managing your listings directly on their platform, they require you to take payment yourself when connected via an official integration partner.
Is there an alternative?
At present there is no alternative.
Do I need a Stripe account to connect to Homeaway?
Connecting to Stripe is the easiest way to collect payments, however, you can set your listing to "invoice" and take payments yourself outside of Uplisting.