I decided to do some back of the envelope calculations to see how this might work. I hope I've got this right, so here goes.

Taking figures for the Mercury Atlas system as an example (all figures approximate) and using metric tonnes (1 metric tonne(t) = 1000kg), total weight was around 120t. 1% of this (1.2t) was the payload (i.e the capsule) and 94% (112.8t) was the fuel.

So just to make this clear, if you want to launch a one tonne payload into orbit, you need a heck of a lot of fuel. The larger the payload, the more fuel you need.

If you want to use fuel to get back down again, then let's just for argument's sake say you need half the fuel to get down that you needed to get up. So 50% of 94% of 120t. That's 56.4t of additional fuel. But because you have to take this extra fuel all the way up, it becomes part of the payload. So add 56.4t to your 1.2t capsule and your payload is now 57.6t. But since we know the payload needs to be 1% of the total weight of the system, that means our rocket is now 5760t, of which 96% (5414.4t) will need to be fuel in order to get the capsule plus the extra fuel for descent into orbit. Subtract the original fuel load and you now need an additional 5301.6t of additional fuel you don't need at all if you use the accepted re-entry method.

So you've turned a compact, simple rocket into a giant beast carrying an extra 5 million kilos of extra fuel you didn't need.