Says we need to nerf some champions, proceeds to name 23 of the only 123 champions in the game.
League is a fickle game. It can't be balanced. 123 champions is a LOT. As the meta shifts, play styles change, etc... different kits are going to be valued differently and new champions will rise to the top.
So if you can't keep 100+ champions perfectly balanced what do you do? You balance in cycles. This group of champions gets to be a little bit stronger for a while (and if any get too strong they get toned down). Over time this shifts to new groups of champions. Some few champions with 'toxic' kits (e.g. Poppy) are pretty much never allowed to be strong until they get reworked in to something healthy in the game. Other champions with kits that fit the predominant play style (e.g. Jinx) will typically remain in the 'strong' group for considerably longer periods of time than other champions. Overall though, champions will shift in and out of this pool. Your mains will cycle through tiers, for example Tier 2 -> tier 1 -> god tier -> nerfed to tier 1 -> further nerfs now that he's been identified to tier 4/5 -> not seen and compensation buffs to tier 3/4 -> eventually small buff or change brings back to tier 2 -> repeat.
I've literally watched Hecarim (one of my mains / my previous main) go from being consistently placed tier 3/4 in tier lists in season 4, then fall to tier 5 in season 5, get some compensation buffs that slowly raised him to tier 3, 2, 1, then become God tier of top lane, then a few nerfs to bring him down to tier 1 followed by what looked like a heavy hit that brought him to tier 2 or 3, and now he's back to tier 1 Top lane and tier 2 Jungle.
Maybe some champions need nerfs. It sounds though like the champions you main simply aren't god tier / tier 1 right now, and you just need to wait for the cycle to shift them in to favor. Which could be a while, and is why it's good to know how to play some other champions so you always have someone that's in favor.