Why does Riot employ the HAMMER approach to balance?

Are you guys intentionally rotating OP picks rather than actually trying to reach something closer to objective balance? Why is there this huge disconnect between balance and what you do? For example, Corki needed some nerfs (maybe lower base damage on R early, some CD increase on W etc.) but instead he's hit by a massive R nerf which makes him a terrible pick for either ADC or Mid. Now, LB also needs some nerfs but she's hit by a huge swing of the nerf hammer with both her ratios and base damages crippled on W. Some changes, like nerfs to AP Kog on the same patch as the Rylai's nerf seemingly come out of nowhere. The reverse happens too. For example, the buff to Lethality while simultaneously buffing items didn't lead to a surprising result when champions like Kha'Zix (who was already strong) were untouched that patch. Now, on the other hand, I think Edge of Night might even have been hit a tad too hard but that's a separate discussion.

Even to someone who isn't paid to balance the game, it's incredibly obvious that this is NOT correct or logical if you want a game with diversity and fairness. Why is there so often this garbage or god tier dichotomy in how Riot balances? You guys release a patch every two weeks so such an ungranulated approach is bizarre and nonsensical to me. It's actually really frustrating and makes it hard to grow attached to and invest in popular champions.

BTW: I don't even play LB and I can still see this will lead to a 45% winrate at best. Even before the Corki nerfs, I predicted 47% winrate at most and was pretty much spot on. I realize that average winrates are meaningless and only games by experienced players can shed light on the power of a champion but in both cases it seems way too severe. I can come up with dozens of other similar examples too.