I’m saying the math works like this when you apply it. There used to be a time when it was perfectly ok to say “The operator needs those 340 p.e. and a little extra to run a pool”. Economic realities have changed since and now 340 are worth a lot more, which of course we are all very happy about. It also means, that no one can honestly still claim to “need” those 340 p.e. to run a pool.
Aside from (subjective) fairness, the math also says that eventually all stake will cluster around k saturated pools. The 340 is the deciding factor in that - it essentially makes large pools more attractive than small ones to achieve that convergence toward k saturated pools.
What I do with the payback scheme is essentially working for the benefit of the delegator. It essentially makes a small pool as attractive as a much larger pool because the effective cost is similar. For me its currently not a problem that I do this non-profit.