Is there an accommodations website centered around trading stays?

When Airbnb came on the scene, it seemed many (including myself) used it to make travel less expensive. But it has become increasingly popular for hosts to use it as a significant income source (also driving many cities to impose legislation against it to prevent neighborhood disruptions and rises in housing costs).

Couchsurfing.com has long existed as a more casual, unstructured option.

But are there any websites that are centered around stay swapping or a credit-based system for homestays? Such a system would seem to facilitate cheaper travel and encourage many of the positives (social interactions, organic city experiences, maximizing housing usage) Airbnb favored without some of the negatives.