SEO ruined the Internet because it made SEO essential to be seen in relevant search results above other less relevant search results. In other words, less relevant search results can often be seen on the first page along with more relevant search results, or even sometimes instead of relevant search results on the first 2 pages of any reputable search engine.
Also, Internet Reputation companies have proven that SEO and fake content can be used as a weapon to push relevant search results so far down nobody sees them anymore.
Finally, how many times have you searched for something just to come across some random webpage with just a bunch of word salad that happens to somehow be relevant. An easy example of this are phone numbers. You search for a phone number that called you and chances are you won't see much relevant data. Just a mix of "robocaller" reporting websites -- usually with no information and random websites with just a bunch of phone numbers in sequential order with no relevant data whatsoever. Even if it's a business' actual phone number.