Falcon 9 never promised full reusability, only first stage reuse, and it did cause a large reduction in launch costs, as well as pretty obviously representing a paradigm shift considering all the other reusable rockets in development, the surge in funding for space tech startups and megaconstellations becoming practical for private entities.

To emphasize that last point, on the back of Falcon 9, Starlink represents over half of all satellites in orbit and Falcon 9 itself accounts for nearly half of all orbital launches in the past 2-3 years. The lower costs are also evident from the fact that many lower budget NASA missions which would have previously had to rideshare ended up just getting a dedicated F9 for less than the rideshare would've cost.