Because it's not "only" about who gets to ball first, but controlling where the ball goes after kick off. If say for 2 players where 1 can always tip the ball away and still keep possession of the ball after kick off, it's very advantageous in 1s, slightly better for 2s, and okay-ish in 3s if it doesn't get pinched and heading directly to goal.
So in 1s, if you can control where the ball goes after kick off, it's like you have 2~3 goals lead just by having kick off goals. If your goal is to save boost and control where the ball goes, you still need to learn speedflip or read the speedflip so you can control the result of the 50s. But you can't go too slow otherwise the speed flip have a free shot on net if they choose to.
On 2s and 3s at higher rank there are different meta but generally it involves losing slightly to your side so your tm8s can follow up. You still can't just lose out right (not touching the ball at all during kick off, unless it's fake kick off position. )