I dont think I am quite understood here.
You can have fuel for 10th alternate with destination closed, you commit to one of them and than SINGLE suprise, SINGLE event like rwy blocked can mean disaster.
Of course as Captain you can take more fuel but it should be dealt with at the planing stage. Your Flight Plan should protect you from SINGLE eventuality.
having said that it looks that i'm the only one having problem with this so it must be me. If you can't beat them, join them.
thank you for time spent on discussion