It's the same for all bulbs, they need the leaves tl provide the energy for next year's flowers. Bluebells not usually a problem in a border as other plants can hide the dying leaves. If they are in a more woodland setting, the leaves can be seen more, but just accept it as realistic wildness
Lily Pilly said:
Allow to die back but I have had a tip this year. Rather than split and plant in the greentake a brown paper bag and collect the heads, when the seeds dry off just scatter. I have been promised this works well. I am going to try it!