You don't need all the champs

There are currently 134 champs in League of Legends. I own all champs except for 18. I mainly play about 20 of the ones I own. If a champion looks fun to you, buy them.

But those who think you need them all to rank up are vastly mistaken. I have four friends from high school that are Diamond and don't own them all. They play three to four champs in ranked. They play them not because they're OP, but because they enjoy them. If you think a champ is fun, play and master them. You will rank up with practice. Look up na.op.gg (click the Champions button and select a champion) You will notice that every champ in the game has been in Master or Diamond. The vast majority of us (99%) are not in this rank tier and shouldn't worry about vast champ pools.

So I'm confused why some of us are complacent with the BE gains and capsule drops. Can somebody explain why everyone needs all 134 champs at once to have fun or rank up? I'm a bit confused. Thanks.