Question why is it so easy today to build reusable rockets? Is it because the onboard cpu speed of the chips can solve more granular control problems with low latency?
I mean, it's been around as a concept since at least the 50s, but there was quite a lot of scepticism that it was worth the cost (this would only have been reinforced by the Shuttle, whose 'reusable' engines were a bit of a disaster)