Why are there neutral supply depots in some Starcraft 2 maps?

In some Starcraft 2 maps, there are lowered down supply depots near the ramps of starting locations. I just don't get why they are for. I thought they were a replay thing until I saw them in my own games.

Is there any way to take advantage of that?


Solution 1:

These exist to make it impossible to block off ramps from below without first investing in the troops necessary to destroy the obstructions.

It's a map feature designed to make it harder to exploit the high ground advantage when you're turtling, or blocking your opponent in with cheap buildings and a small army.

Pylon block