Recently I've noticed more people requesting evidence or proof for an answer. This is mostly a good thing - backing up a substantial claim is great (especially if you summarize it to prevent link rot). However, this can be taken way too far. Consider the following:
In Super Mario Bros., Mario is capable of jumping. 
Obviously, demanding proof of this is of little help to anyone. If you've played Super Mario Bros., then you clearly know this. Such an example is common knowledge, and I think most of us would agree you don't need to prove something like that (we aren't a court of law, after all).
Next, let's consider the extreme opposite.
Luigi is a playable character in Super Mario 64. My uncle works for Nintendo and showed me how to unlock him.
This kind of claim absolutely does require proof. Not only is it making a strong claim, it's relying on an unverifiable source. Asking for proof here is absolutely necessary, otherwise this answer is little more than a schoolyard rumor.
That's all well and good, but there is a vast gray area between these two extremes. Here's a third example, from an actual question (note that I'm not singling anyone out, this is something I've seen multiple users do across multiple different comments): https://gaming.stackexchange.com/a/237675/107588
This answer has definite problems, and it was downvoted as a result. However, what I'm addressing is the request for proof. If you've played the game in question, this is something quite obvious that can be readily and easily demonstrated. There is no need to request proof for this.
Basically, how should we handle these sorts of situations? I'm concerned that if we're requiring proof for everything we'll stifle the potential questions and answers as "proving" some things is trivial and not really helpful to anyone. Furthermore, what DOES in fact constitute proof in the last situation? And who exactly are you trying to prove it to?