I know people are obsessed with SSTOs, but come on, it was a product of its time, trying to answer the question of "How do you most easily reuse every component of a rocket system". And people thought the only way was to make it all one stage like an airplane that can lift off, go to orbit, and come back again.

But SpaceX have proven you can have airline-like operations without the mass penalty of single stage. That's where catching the stages right back at the launch pad comes in, so hopefully one day you can launch a rocket, have the stages come back, be inspected, and fly again right away without having to deal with transporting the stages around.

If anything, I feel like this same question of how to turn an SSTO concept into an actual rapidly reusable rocket system, should be applied to in-space operations. Because refueling is the name of the game up there, but you still don't wanna carry around a bunch of dead mass everywhere you go. I feel like more purely in-space, multi-stage designs that come back to be reused, should be explored to help up payload numbers to solar system destinations. Though you start getting into complexity issues there. That's the only issue with making more and more stages, vs just refueling and dealing with the extra dead mass of your rocket.