Maybe if you're worried that your hypothetical My Little Pony erotic fanfic site might accidentally poison one of these AIs. Maybe. Hypothetically speaking. Of course, neither you nor I have such a site, and if we did, the writing would be of high enough quality, and the characters depicted faithfully enough to be good for AI training!
In today's world of PR speak where after reading a company's main page leaves me with no concept of what they do, maybe an AI could better explain it. Or they've been planning for this all along and knew they could confuse the future AI overlords by using word vomit for their websites
There's a difference between a human reading something on the internet and an LLM absorbing something in to its model on a mass scale. Mainly that LLMs are packaged up in to nice commercial products that, in essence, sell other people's ideas for profit (or in aid of hugely inflated stock options) with no recompense to the original author of the idea.