the average is actually 7.9
https://mangadex.org/stats/other
so that should be more or less "our" 5 here, anything with 8 here is average.
the problem is not the system, the problem is the user and their voting tendency. as long as people won't stop voting with just 10 and 1 (hint : they won't), the average rating will just stay up there.
it's that old
hate out of 10 again.
Before we got our current "weighted rating" I chip in that we do weight people's vote to their vote tendency like what anidb do, hence people who spread their rating will have a higher impact on weighted rating than people who just vote 1 and 10, or only rate stuff with just 8910 or 123 or 567 (you know those people, either those manga fanatic who judge that all manga are perfect, edgy person who overly critical without reason and think 4 is generous already - but give 10 for edgy series, or those who try to be fair but too afraid to give slightly higher or lower score which ended up skewing their rating tendency anyway)
but the admin opt for
bayesian rating instead.
I'm not saying that the decision is wrong, it's just that - in this case - it doesn't address the main issue, the voter themselves.
when bayesian show lower rating people still tend to rate 10 to "bump the rating up". but when everything are rated around 5-6 and they are told that "your vote weight less if you keep rating stuff with just 8 9 10, so the more you vote 10 to bump the rating the less your rating weighted by the system", then at least they'll rethink their voting behavior. doesn't means they'll change though, but that might makes them thinking.
But in the end, there are no silver bullet on this matter, anidb's weighted rating also criticized by people who hate seeing their favorite show a 4-6 rating (eventhough that's like... the average) and that it's "unfair". you'll also meet rating which is unthinkable in most other site, like
isekaied high school prodigies with 2.4 weighted rating...
also, ranking or anything like that would just thicken the problem, the more stuff people could use to justify their taste and inflate their ego, the more they'll try to play with it. it's not a secret that
MAL have problem with duplicate account trying to skew their rating and that's been a problem
for a long time already.