I like vehement arguments even when I disagree with them. Based on this man's logic, if I were to run a web forum then I must provide an API or data dump to download the posts created by the users? How about a comment section on my blog? How about a community Discord server? Why not Facebook posts? Or Instagram stories? I often get the feeling that in these circumstances people derive first principles from specific d…
I notice this also when people are talking about "the spirit of open source." No, open source licenses are licenses, not spirits, and you were contributing huge amounts of time and effort to fill a platform with content that you have absolutely no control over. People don't owe it to your OSS project not to fork it or not to become more successful than you at distributing it as a service, and Reddit can do whatever they want with your content that doesn't violate any obligations to you set out in their ToS.
Next time, do AGPL or proprietary, and don't give away any content that you value to someone else's platform for free. If you want them to be obligated to distribute it for free forever, you really should be paying them.