You can gather them from anywhere they exist. There might be places where it is easier to gather facts than Reddit.

But wherever you get purported facts, it's hard to know whether they are merely claims, or actual facts. Most of us do indeed short-circuit our evaluation of claims when we trust the source, and although this sometimes causes us to wrongly believe false claims are facts, I think it's probably a good optimization on balance.

Nevertheless, "who should we believe?" remains one of the most fundamental questions of human existence. The tremendous energy required to confirm the factuality of even a trivial claim makes me agree with what I think is your premise — the quoted poster was making a highly dubious assertion of "facts".

But I think s/facts/claims/ would suffice to fix it.

on edit: note I do not say anything about verification, as that is a different thing as to whether or not a thing is a fact. Verification is about how sure the knowledge we have is a fact, but whether a fact is verified or not it remains a fact even if we do not know it is a fact.

Source?

How do you define reliable?

Why is the authors identity important?

Facts don't change because you know the authors name, or trust the source, or like the person telling lies.

The idea that anonymous sources, or "untrusted" sources (for someones definition of trusted) cannot be the source of facts is gaining ground right now, and it needs to be pushed back on wherever it is seen.

It's a lazy Ad hominem, and it's down right dangerous.

I don't care if it's elected officials claiming Russian malinformation or a random chess thread, this is the hill I choose to die on.

Which mythical reliable sources? Humans are known to make errors regardless where they work.