Businesses who need blog posts for content marketing would hire copywriters who would paraphrase my content and publish it as their own. Now they can do it faster and for free. Blogspam got cheaper and more effective. This applies to other kinds of spam too: email spam, forum spam, comment spam... Spam spam spam. I'm afraid that we'll soon drown in even more noise.
Again, this is just the current implementation, which has not reached its full potency. We're already seeing this combined with voice and video generation. Then it's students doing their homework with it, and even professionals.
This is a game changer. You can argue that it makes the game better or worse, but you can't deny that it's changing the rules.