Can't wait for the specific examples
So many parroting the same "bias" line here, yet not a single example has been linked.
This kind of bias is a statistical measure; typically you can't prove or disprove it using a single sample.
It's about larger patterns, which things are talked about and (crucially) which are not. How much attention is given to things and not.
What for? To start a flame war? No one is going to get convinced one way or the other.
Which was why I just wanted to point out that while I think Wikipedia is a net good overall, it is not without blemishes.