Judy, Although the premise DOES stem from a somewhat legit base, this is basically baloney, and being used as a sales tactic.
Drain tile which does not have a "sock" (a cloth mesh sleeve surrounding the tile itself), can allow small sand and some soil to enter the tile, flow to the sump, and be washed out. However, the tile on the outside of the home is laid on top of the footing, so any soil it might obtain will be coming from above; and the tile inside is beside the footing, and is completely surrounded by sand.
The soil directly below the footing is supposed to be 100% UNDISTURBED soil; if they dig too deep in one are when preparing a footing, the footing becomes thicker; you do not add soil back in to fill the low spot. So the soil below the footing is tightly compacted by nature, and does not just start falling apart and "going down the drain." Part of the entire premise of having a drain tile outside, and a tile inside, is that water on each side is collected separately, thus it is not trying to "wash" below the footing.
I have seen drain tile clogged with sand, but it's rarely an amount of concern, and you can find a little sand in the bottom of your sump well, but you WON'T find the base from below your footing there.