Why is it frowned upon here to 'steal' content from reddit?

If anything, shouldn't it be encouraged, and even automated? I'm including even the 'old' stuff from reddit here. Reddit shouldn't be the absolute owner of the content submitted by users. When I migrated here, it wasn't because of me being against reddit users, but being against reddit the company. Copying the content here actually hurts the company in sense that they don't get to then gatekeep the crowdsourced content.