Here's why:

* Convergent Boundaries: These occur when two tectonic plates collide. The denser plate subducts (sinks) beneath the less dense plate.

* Subduction: This process of one plate sliding under another results in the destruction of the oceanic crust. The subducted plate is melted by the intense heat in the Earth's mantle, and the molten material can rise to the surface, leading to volcanic activity.

Types of Convergent Boundaries:

* Oceanic-Continental: An oceanic plate subducts beneath a continental plate. This can lead to the formation of volcanic mountain ranges and deep ocean trenches.

* Oceanic-Oceanic: One oceanic plate subducts beneath another. This can result in volcanic island arcs and deep trenches.

* Continental-Continental: When two continental plates collide, the crust buckles and folds, creating mountain ranges. This is not technically "destruction" of the crust, but it does involve significant deformation and uplift.

In summary: Convergent plate boundaries are the only type of plate boundary where crust is destroyed.