OK I'd gather you're dealing with someone I'd probably consider a woo-woo or zombie sheep depending on their affliction. (Woo-woo think the likes of flat earthers where if any two of them a couple hundred miles apart, had mobile phones, a spirit level and a tape measure would surely discover for themselves the concept to be in error, vs a zombie sheep more often simply followed a rabbit hole past any point provable fact and simply believes, trusting the people responsible (content creators) are experts / totally credible and would not lie to them.)
Sadly in recent years the number of people who've lost critical thinking and constructive communication skills has been growing and zombie grooming news and social media areas certainly hasn't helped the situation. Too many people can sit in a social media area safe from legitimate discussions that might challenge any poor or poorly informed ideas they have, and instead they can hog down on a content feed that more than likely allows them to reaffirm some beliefs they already have come to see as fact.
People with very warped views are usually hard to reason with, typically it's not a case of just summing up the facts or making a very good argument to reason with them, typically the problem is dealing with their denial[1]. Pretty much even in real life is the same as dealing with someone online who is also Stone Deaf [2] For instance presently I have a brother who has followed a youtube rabbit hole and has wholeheartedly bought into the idea that Limosilactobacillus reuteri [3] has become somewhat near extinct since 1950 so much so he invested in a kit to grow them to help supplement his diet ... even before he handed over any money, he carried on like a pork chop ranting / screeching when I've informed him that it's not that extinct - insisting instead the areas of the internet I'm read where it's reported / suggests not that extinct ... those areas are not very factual ...
The Dead Internet Theory. Not heard it put quite that way, though I know in the 00's to have noted those convinced []The Matrix[] was their reality, and from late 00s I'd noted many netizens complain the web was dying but were often dismissed as many were simply moving to social media and the person complaining just needed to get with the times. But as a theory - well yes and no and the idea the net was dying has long been asserted by numerous people including myself but for entirely different and more levelled reasons - I find it quite amusing that this present concept includes AI fears and world wide effort to conspire some large scale smoke and mirrors for nefarious reasons.
On my time off, not at work after 2002 to about 2015, I typically found myself online most nights conducting a great number of searches on behalf of various people online at forums who wanted certain and accurate information or driver files for obscure equipment from the 90s. By 2012 I was certainly trumpeting the issues to be had with any success on my part, might be not much better than their own efforts as various companies and entities were actively fighting against any sharing of technical information which would be very useful to the DIY or fix it yourself market, more popularly by obfuscating the information though various methods like []Flooding[] -- something which I had observed for quite some time. I don't know how many time I looked for engine settings and got thousands of BS sites advertising manuals (most with all the same template) and for a time easily beaten as there were working search tools to filter out 99.9% of the BS from the results required. Albeit the truth of endless low quality sites and information of the net and inability for search engines to just ignore it is somewhat more benign than a world wide conspiracy to befuddle the population -- but of course what better way to dispel, disprove and discredit that any company or other entity are seeing off useful information, by whatever means such as filling up much of the searchable net with scam / spam rubbish results and sites, than to promote a conspiracy that's an over-the-top, mutated and extrapolated version of reality and dangle it for the unsuspecting ever vigilant zombie sheep whom are near always 100% sure they'd know BS if they ever saw it.
As an example of where information is simply seemingly removed from the web, try finding the always present component in extra virgin olive oil that some people react very badly to. I was surprised recently to find that tracking down that information was not possible via various search engines, and yet in the 00s when I first found out I was n fact not alone and searched online, I'm sure even wikipedia had information in regard to that troublesome component which is removed with lots of refining and somewhat safer for those like myself, who react not so well to extra virgin olive oil (EVOO). Instead present day results at best, suggest it might cause some people discomfort due to contamination or various processing procedures eg [4]. From what I first ran across back in 00s via multiple sound sites, it was present in all EVOO and refining the EVOO to death allowed people like myself and those who react much more violently, to tolerate the resulting olive oil better - of course I just avoid it and anything made on the oil just to be on the safe side.
[1] https://www.simplypsychology.org/defense-mechanisms.html#Den...
[2] https://www.politicsforum.org/flame-warriors/
[3] https://en.wikipedia.org/wiki/Lactobacillus_reuteri
[4] https://onlinelibrary.wiley.com/doi/abs/10.1002/978111846041...