Everyone should try support and jungle
I'm not saying in ranked. Or as your main. Or that it should be compulsory. But I think everyone, for their own good, should play 5-10 games as support, and 5-10 games as jungle a season, at least. Not mandatory, just by choice they should go and do it. And not as a troll pick, as a normal, meta support/jungler. These roles teach you so much about team play, objective play and reliance on your allies. On top of that, you will understand these roles better, be able to play with them better, rage at them less, and learn useful skills. You will probably get better at warding, playing safe and general map awareness.
Real talk though. Autofill, like it or hate it, you will get support and jungle sometimes. I am a jungle main, but I picked up playing support a lot in normals, so that if I get autofilled to support, it's cool. Everyone, everyone should know how to support. It is a cornerstone role, you will be forced to play it sometimes, and it teaches you more about map awareness and warding than arguably any other role. Most people should know how to jungle, it is crucial to objectives and swaying lane balance. More importantly, you will know what a jungler must do, and how they function, so in your primary role in ranked, you can know what to expect from them, and how to work with them better.
This isn't to thrash anybody, or say any role is bad. It's just saying, autofill and good teamwork, demand that we all get better at support and jungle, because these are huge roles that function totally different from top carry, mid carry, adc carry last hitters. And if you don't know how to jungle or support, you can't just fudge it. It's not like a mid main getting top and still knowing the basics of laning and last hitting, picking somebody like swain, vlad or cass top to get by. It is a totally different aspect of the game. Learn it, for your good, your team's good, and your ELO.

Now that was uncalled for. (>_>)
, which allows me to solocarry the game, so I dunno.
.
Though I think support has taught me the most with the game, especially positioning due to how squishy some supports get and warding/jungle paths- since most but not all junglers tend to appear after the 3 minute mark or whenever my adc and me think it's a good idea to be by the enemy turret. xD
But my heart belongs to my supports, mainly
. c: -gives you a hug
).