This article is kinda funny, the person who made the website is pretty clearly just some tech dude trying to make money off something he did for fun.

The site also advertises sale of its scraped data for other purposes. “Interested in training an AI model with Discord messages? Are you a group of federal agents looking for a new source of intel? Or maybe something else? We've got you covered. Contact us and let us know how we can help,”

By the way, this only pulls from large public servers, he's just scraping messages en masse. Stuff like private servers and DMs wouldn't be affected.