In case you didn’t know, you can’t train an AI on content generated by another AI because it causes distortion that reduces the quality of the output. It is also very difficult to filter out AI text from human text in a database. This phenomenon is known as AI collapse.
So if you were to start using AI to generate comments and posts on Reddit, their database would be less useful for training AI and therefore the company wouldn’t be able to sell it for that purpose.
You can train AI models on AI generated content though. AI collapse only occurs if you train it on bad AI generated content. Bots and people talking gibberish are just as bad for training an AI model. But there are ways to filter that from the training data. Such as language analysis. They will also most likely filter out any lowly upvoted comments, or those edited a long time since their original post date.
And if you start posting now, any sufficiently good AI generated material, which other humans will like and upvote, will not be bad for the model.