I agree with attaching in line with lift arms, but have never saw the need for a center hook. I always attach my lifting chain to both hooks, then drape and connect the hook to the chain in the center of the bucket to center how the chain hangs. It’s stronger because the weight is distributed to both hooks, yet the lifting chain is centered.
My thought process is that connecting a chain across hooks aligned with the loader arms, assuming you could even get perfect force distribution, would be equivalent to connecting to a hook mounted dead center on a rigid steel bucket. Built-in perfect force distribution.
This does assume the lift/pull capacity of the loader wouldn't be enough to cause the bucket structure to fail. I personally pull a lot of t-posts and hit the tractor's limits occasionally (t-post grown into roots etc) and don't feel I'm pushing the limits of the bucket by any means.
Any tugging and jostling with two hooks would alternately send loads to either loader arm. Maybe in reality that's inconsequential.
I've got decades less experience than many people here. Could be things I've never considered.