why do you say that? There are a lot of items in the game that raise your abilities over 20.
In 5e? There actually are not. There are a few - a very few, and none of those very few items stack with each other; this is by design. To my knowledge, there are the tomes; very rare magic items that you generally can't just decide you want, and each with their 100 year cooldown, and there are the strength belts. I don't think there's anything else.
The natural 20 cap includes - and should include - racial modifiers. They do not, and should not, stand outside it. This is important to the system as well, but more than that, it's to underscore the intention that anyone, regardless of their race or background, can attain the same pinnacle of excellence as anyone else; that's kind of the point.
