Someone that pays for a Red Hat subscription is effectively outsourcing a lot of tasks that need to be done if you're going to use open source responsibly in a large organisation. By paying us, our customers get to benefit from it being done once, and well, rather than each of them having to duplicate that effort.
Paying an organisation like Atlassian or GitHub to think seriously about encouraging effective collaboration amongst software developers and others should be something large enterprises do as a matter of course. Yet I'm not confident either company could AGPL their core applications (as they exist today), without seeing a lot of potential revenue disappear down the drain.
Tim O'Reilly coined the wonderful phrase "Create more value than you capture", but there's an unspoken corollary to that: "Capture enough value to thrive".