Why Is Balancing so Hard?

I'm an avid MTG and LoL player.

For those who may not know, around 2016/2017 Magic was in a tricky spot. Balance was AWFUL. Multiple cards had been banned in the standard format, and that had not happened since the Mirrodin block. So how does this relate to LoL? Well, both games have similar ways in which things can be unbalanced.

Reason 1: Playtesters don't anticipate X becoming powerful/weak. I get the feeling that often Riot releases buffs/nerfs thinking that they're fine, only to realize they are not and are too impactful. Similar to how some Magic cards had to be banned because they seemed fine in play testing, this seems to be the case for a lot of Riot's balancing problems.

Reason 2: Kits are too synergistic within themselves/overloaded. I mean, look at Akali. Her kit is just overloaded with dashes (and possibly damage). Essentially, your abilities are cards. And using an ability is like using the card then getting it back when it's off cool down. But this is a problem because some things are fundamentally broken when they can be abused in too short of a time (i.e. the old 40 lightening bolts and 20 mountains). It'd be like ALWAYS having X card in your hand. It's broken.

Ideas on solving the issues:

For case 1, I suggest getting some one-tricks to test the changes first. Having a team of pro players playlets cards before release has been considered by the Magic community, and I think getting one-tricks to test changes would be amazingly helpful for Riot.

For case 2, I think Riot needs to better define what constitutes different Classes. Akali is broken (to a lesser degree than before, but still) because her shroud breaks what Assassins are supposed to do. It provides too much safety which is not what assassins do. Look at Kai'sa's E giving her AS and Invis, her ult giving a shield, her passive giving an execute...none of these are really things marksmen traditionally have. Riot needs to push the envelope while still maintaining the classes consistently.