Why is normal matchmaking such crap

I mean, by all means, I love it when golds are on my team because it makes me feel like maybe I'm a little bit awesome, but why, after I'm level 30, is there any reason for me to be paired with people who are under level 30?

Like a level 25 ADC Vayne who has no idea what they're doing?

Or a level 17 Anivia support who is probably a smurf and spends the whole game troll-walling me after she feeds bot lane? Or a level 25 Jinx that has no idea how the game even works? Or a level 24 Kayle? In which the above three were obviously a trio queue--which leads me to ask WHY WAS I PAIRED WITH THEM IF THEY ARE ALL UNDERLEVELED?

I mean, but on the plus side the other team had a level 12 Taliyah support and a level 19 Pantheon, and then 2 silver players, so..."balance"?

And yeah, I get it. If I want to play with people "around my level" then I should play ranked and only ranked. Except my ranked teammates would probably appreciate it if I didn't try new champions and builds for the first time in ranked, hence norms.