History lesson

The biggest reason people hated oko when you played against him is how stupidly hard he was to remove. He would keep neutralizing creatures and shutting down the opponent's board or churning out more (slow) threats, and decks really lacked ways to kill him. Even if he was in standard he would be hard to kill, 6 loyalty is gigantic
The reason he'd still be trash in right now is that you don't need to remove him
Every deck wins the game with tools that oko can't interact with. He can't do shit against haste flying creatures, mass tokens, combos, etc etc. Oko can come down and +2 and make a food and so what? Opponent will just totally ignore that oko exists. He could make a 3/3 creature the next turn and good job you've effectively played a 3/3 for 3 that can't block its first turn. I mean fucking hell you can't block aggro with fog bank or glissa or 0/8 for 2 what do you think an elk can do

If you're trying to win the game with a bonecrusher giant and lovestruck beast sure oko gums up the board and doesn't die. The only thing he'd do against cori steel cutter or slickshot showoff or esper pixie or jeskai control is... lose. Look at the list of most played creatures in standard, which ones would care about oko? Sheoldred and oculus pretty much