Op ... I suspect that by now you know that your friend is in fact an idiot, so I won't be telling you that again.

It goes even further, though.
Full suspension mountainbikes, the ones with suspension for the rear wheel, are meant for actual jumping and falling down.
That's the reason these things exist, mainly.
If you're not jumping or falling down from heights, you will never have any actual benefit from the rear suspension.

In all other cases, you can use the suspension of your legs.
Learning how to use your legs as suspension is what you should do.