Stalactites doesn't cause damage to the player when flying into ceiling using Elytra

Vertical falling onto stalagmites multiplies the fall distance by two to calculate the total amount of fall damage, using the formula ceil(fall_distance × 2 − 2).

It is logical to assume that a vertical flight (falling up?) using Elytra and Firework Rockets into stalactites will deal twice as much damage to the player as he usually receives because of flying into wall (wall or ceiling?).

But in fact, the player receives only a small amount of damage or does not receive it at all. It seems to me that this is wrong, because Pointed Dripstone are as sharp on top as they are on the bottom. Also it's impossible to create player traps from which it's impossible to get out using Elytra w/o dying (for example, from a pit) because of this (bug?).