What is so wrong about ADCs being glorified tower pushers?
The point of the game is to destroy the enemy Nexus. But to do that you need to destroy an inhib. But to do that, you have 3 towers impeding your advance. Calling them a glorified tower pusher, is basically saying that they are THE most useful class in the game. No other class can itemize AD, AS, and ArmPen for taking out towers(as well as having sustained damage over time for killing tanks, when items like Banshee's means your APC may need more than a full rotation to kill one) except for the melee carries. But the melee carries can't take a tower down from range. They have to be standing next to it, and as such are more vulnerable to the enemy team. If you lose a teamfight, but the enemy carry is dead, you probably bought your team some time as everyone on the enemy team is hitting the tower with a wet noodle. You may still lose it, but if the enemy carry was alive, you'd have lost 2 towers, or maybe a tower and an inhib.
Let's say your team lost an inhib and now super minions are flooding your base. Sure you may have a Ziggs, or some other wave clearing mage, but they won't be able to clear out that super mnion wave as good as an ADC. Ziggs hits a wave with everything he has, probably kills a few minions, and chunks the supers, but after a while will need to fill up on mana. But the ADC hits one at a time, while criting it for around 1k damage, and does not have to worry about a resource, and if there is a lot of minions, they can facetank them, and LS the health they are losing back.
I honestly see nothing wrong with ADCs being nothing more than tower pushers. What are assassins, but glorified killers. In the most balanced of cases they kill one person, make it a 4v4 for a while until their skills come off CD, and they can help the team, although teamfights should be over by time 3/4 of their rotation is back up. Mages, are either wave clearers, or AoE nukers. As an AoE nuker, all they do is kill people, which ADCs also do, but they suck at taking objectives. Tanks are glorified meat shields, that just stand there and press buttons in order to CC the enemy team. They just got to hope no one on the enemy team is fed so that they don't get melted. Support, are like tanks, that can't take a hit (bar Leona, Braum, and Taric. Not counting Thresh as he has no inherent tankyness, he just builds tanky, which anyone can do. Him being a CC bot, allows him to get away with it.) Lastly, fighters are a mess of a class, with no real specialization. They get out tanked by tanks, out DPS'd by ADC, and APC, and don't peel as well as supports generally do.