I assume it varies by platform. Meta has a service that makes data available to vetted academic researchers, for example, so keep in mind that "available to researchers" does not necessarily mean that one can just post a link to it on Hacker News.
If there's a specific platform you're thinking of, there's probably someone in here that can direct you to the right place. What platform are you thinking of?
If there's a specific platform you're thinking of, there's probably someone in here that can direct you to the right place. What platform are you thinking of?