I really think Lemmy, Kbin, and Mastodon need to figure out a way to have a default terms of service that ship with their product which forbids using the API to collect data for commercial purposes.
Additionally, there should be a way for users to indicate licensing for individual posts, with a default license instance admins can set.
That way for-profit instances could be forced to filter out posts with licenses that do not allow for-profit use. Honestly, even just a simple check mark "[ ] allow for-profit republication", and have two licenses that can be attached: one that allows for-profit use and one that does not.