SEO is ads Google is failing to monetize.
That said, the reason the Reddit trick works is that it uses information Google explicitly excludes when ranking content (engagement signals).
Google has a bunch of “objective standards” that it uses to paternalistically shape what the web looks like. Many of these are divorced from what users actually want for pieces of content (https, AMP, a life story in front of recipes to demonstrate authorship, etc).
As explained in another comment [0], the real reason the Reddit trick works is that Reddit content is hand-curated by humans who are dedicated and passionate (and, I think, also work for free). It's a garden in the jungle.
But there is no conceivable universe where seo spam isn't the arch enemy of Google. Google needs to fight spam to survive, it knows it and it does. But that's hard. So hard in fact, that nobody else has cracked the problem, and for all the anecdotal evidence of someone switching to Bing, Google's marketshare is still utterly dominant.
The Dead Internet Theory may have some weight: Google hasn't dropped the ball, but it is slowly drowning into the sea of "content-free content".
But if that's the case, so is everyone else.