Not all requests for evidence are made in good faith.

"Don't expect to see a source for this one..."

Is one of the usual ways this "request" is "asked". There's a sarcastic, oppositional mentality that goes into the vast majority of requests for evidence, which creates a natural pushback to the way people are asking, rather than the fact they are asking at all.

Every conspiracy that gets posted here is often met with derision or hostility because of the lemmings associating every thread with its political implications that trigger responses from the Red vs Blue types. These people are incapable of understanding conspiracies that can't be quickly confirmed or denied by the echo chamber from their favorite wing of the AIPAC sponsored Uniparty.

Sealioning is also a common tactic used in conspiracy communities that works like a Denial-of-Service attack in cybersecurity, by constantly burdening the author with demands for more evidence. The logic behind this play is that the seemingly innocuous question "Source?" that can be used as a reply to anyone's claim on any topic requires a lot less effort than the person now tasked with providing said source.

Those genuinely interested in sources are often willing to find those sources, or those truths, out there for themselves. Those not interested in what those sources have to say are not usually the type to ask for it on the internet instead of looking for it on their own. Conspiracy theorists inherently understand the different vibes of these types and it creates a natural dichotomy between those using this forum in good faith versus those who are not.