If you haven't picked up on it, over the past few years Riot has been phasing things to largely favor an adc-centric playstyle. There's obviously exceptions and ways around it, but these are largely much riskier and work more in solo queue than competitive play.
Think about pro play... it's tanky bruisers or tanks toplane for the most part. Carries are only played when hella strong for the patch and even then, they're on a time limit unless the other team likewise picks a squishy carry champ.
Jungler's are mostly relegated to being vision control and setting up their teammates to carry even if they get a big lead for themselves. They use their lead to survive after getting the insec that wins their team the fight. Or they're playing knight's vow tank or redemption olaf where their itemization is more about empowering... the adc than about making them as individually strong as possible.
Midlaners used to be able to 100-0 a squishy in mid and late game if they were assassins or burst mages. Now it's 70-90% in most cases. And after that, they have nothing for about 10+ sec during which the fight will have pretty much been decided. They're much more about cc to enable their team to pick off a single opponent faster than the other team can. Just look at stuff like lissandra and galio in the past year or so to illustrate the cc point. Other mids might offer more damage or even outscale, but that's no longer what mid is largely about.
Supports are get more gold, but their itemization is still either generic stats or stuff focused almost exclusively around adc-style champs. Bonus attack speed, armor, tank some of the damage meant to be applied to adc via itemization, shield them from burst damage, etc. Much like jungler, support is often more or less centered around being a stat boost for adc.
Basically, we've largely been heading towards a state of game where adc is supposed to kill 4-4.5 members of enemy team in order to get an ace. Mid kills the other 0.5-1 member largely by themselves. All others are there for cc, to be caught and killed, to peel or engage for adc (often in combo with midlaner), to be a meatshield that absorbs damage until blown up by adc and friends, and/or to be a walking stat buff to adc.
Sure solo queue is a bit different because other roles are more capable of carrying in a semi-coordinated 5v5, but it's still adc-favored game for the most part. That's not to say they don't have their own troubles either, but just that the game is mostly trending towards the idea of adc as the exclusive 1v5 champ at higher level of play. In iron? It's iron and anything can still happen. And honestly, that's the more fun game to watch in my opinion.
for all ins and dominate the lane, or 
and have some clutch ganks for your team. Top is an open ended role, and requires intuition, similar to jungler, to play effectively.