Up until that point, if a rocket slowed down during takeoff something had gone horribly wrong.
Just in case anyone is unaware of the most notable exception:
https://en.wikipedia.org/wiki/DC-X
https://www.youtube.com/watch?v=0IWIv2MKcyg
DC-X has been a major inspiration and proof-by-example for commercial reusable rocket efforts. Its technical achievements and focus on aircraft-like low-cost operations showed a path out of (or into?) the darkness.