The only circumstance where LF will be able to get multiple downs with a single Chainsaw Swing is when a survivor was waiting nearby for the save (I.E. Pallet Stun, Flashlight Blind). However, the killer will need to be running Contagious Fright to see where to go with the remaining time of the Chainsaw Swing.
The situation you're describing was just bad positioning on the survivor's part, and you can't rely on them to always be in a bad position for you. That's like a solar eclipse, you don't see those often unless they aren't high ranked.
Overall, LF is underrated, I agree with you there, but he's definitely not the monster you're saying in my opinion. He's loopable and doesn't have anything to help him in a chase besides mind games. Killers can't win on basic mind games alone, they need something to help them cause pressure on the survivors.
It isn’t necessarily bad positioning, a lot of those loops are short so I can either eat the pallet or get a down, I’m not saying he is a monster necessarily but I don’t think they should rework him, he needs QOL buffs and an add on rework, I’ve actually suggested one:https://forum.deadbydaylight.com/en/discussion/75974/bubba-add-on-reworks-tweaks#latest