It's extremely difficult to write math articles for a general audience which are both accessible and accurate, and the number of excellent writers working on Wikipedia math articles is tiny.

Please get involved if you want to see improvement. There are some math articles which are excellent: readable, well illustrated, appropriately leveled, comprehensive; but there are many, many others which are dramatically underdeveloped, poorly sourced, unillustrated, confusing, too abstract, overloaded with formulas, etc.

Absolutely. I do not know the current status, so don’t kill me if now is much better, because is just an example from many. But take fourier series. I remember going into the article, and instead of starting with something lime “helps to decompose functions in sums of sin and cos”, started with “the forier transform is defined as (PUM the integral for with Euler formula) continues: is easy to show the integral converges according to xxx criterion, as long as the function is…” you get the idea. Had I not know what FT is, I would’ve not undestand anything

Articles in biology, from which I understand nothing, are a wall for me. I could never understand anything biology related. Also for example, in Spanish, don’t ask me why, any plant or animal is always under the latin scientific name, and you have to search the whole article to find the “common” name of the thing.

I find it the other way around. I remember vividly that the textbook I was using for proving Gödel's first incompleteness theorem was insufferable and dense. Wikipedia gave a nice and more easily understood proof sketch. Pedagogically it’s better to provide a proof sketch for students to turn it into a full proof anyways.