Presumably the entire 2005-2023 (up to March) dataset which is (was) freely available on Pushshift / torrents is enough?
Also, not that Sam Altman is unbiased, but he did say that social media (Reddit, Twitter) were not super important for developing LLMs (But of course, that's exactly what he would say if they were useful!)
But sure, there are plenty of other data sources as well. On top of the problem of not wanting to train your data on content you know is littered with bots.
Significant outdated cultural knowledge seems the norm for humans too.
This approach mostly doesn't work because, for third-party client apps that don't go through the developer's own server, scrapers could snag those keys from the client. Scraping has always been a thing and I don't see a foolproof solution that allows good actors to use the product without bad actors getting to scrape content (not that scrapers won't settle for html scraping).
And proxying api calls isn't an end-all solution. This introduces a large burden for the developer to not just run a scalable proxy for the API calls, but also must introduce and manage some abuse prevention system, maybe with their user account system with reputation ratings based on number of times they've hit a rate limit or how many different subreddits they try to access every day.
It also is generally not good for users to have to deal with a proxy like this, since it means the app developer has the ability to log all of their users' usage, and could be compelled by law enforcement / courts to hand over user PII or activity logs.
I think the problem is that the API concerns are more around LLMs having easy access points to their data than anything else. Still, this could have been avoided by providing free-use keys to trusted developers. It's not like there are that many of them. Just seems odd how dark they've been towards this user class. It's very similar to the Twitter changes.
The nuke approach they've done will send so many of their important, core users off the site.