One cannot be DDOSed with junk when not actively trying to stuff as much junk into ones head.
The junk gets thrown at you in mass volume at low cost without your permission.
Let's say a relative of yours who isn't too tech literate is using a search engine to lookup some information, could be presidential election, COVID, some news story. If one of the results on the first page deviate from others, it's easy to notice. But if all of them agree, they became the truth. Of course your first thought is to say search engines are shit or whatever off-hand remarks. But this example is just to illustrate how the volume alone can change things.
The medium doesn't matter, these things could come in many forms, book reviews, posts on social media, ads, false product description on amazon, the problem is the volume.
Of course, these things exist today but the scale is different, just like the difference between firearms and drones or weapon of mass destruction. If you think that it's the same old game and you can defend against the new threat using your old arsenal (in this example: infantry against drones), I admire your confidence but you're in for a surprise.
Sadly, you seem to not be looking further than your nose. We are not talking about just you and me here. Less tech literate people are the ones at a disadvantage and need protection the most.
The social media algorithms are the content curators for the technically illiterate.
Ok, they suck and they're actively user-hostile, but they sucked before AI. Maybe (maybe!) AI's the straw that breaks the camel's back, and people leave those algorithm-curated spaces in droves. I hope that, one way and another, they'll drift back towards human-curated spaces. Maybe without even realizing it.
It's not the best analogy because there's already more junk out there than can fit through the limited bandwidth available to my brain, and yet I'm still (vaguely) functional.
So how do I avoid the junk now? Rough and ready trust metrics, I guess. Which of those will still work when the spam's 10x more human?
I think the recommendations of friends will still work, and we'll increasingly retreat to walled gardens where obvious spammers (of both the digital and human variety) can be booted out. I'm still on facebook, but I'm only interested in a few well-moderated groups. The main timeline is dead to me. Those moderators are my content curators for facebook content.