A lot of data I provide to services is exposed to other individuals so that the service can function. They doesn't mean that data belongs to those people or that they can feely use that data elsewhere.

Allowing unfettered scraping and repurposing of data would have a chilling effect on all types of services. For example I wouldn't necessarily want a bot to scrape my comment history on HN, doxx me, and share my identity and comments with others.