Spaceflight

It's probably because this is all solid stages. Since you don't have throttle control or the ability to stop and start the engines with solid motors if your building an entire launch system built around them you use more stages.

I seem to remember some early US rockets with an unusually high number of stages by today’s standards, so maybe that’s the level of technology this company’s at.

It could point to a limitation of the rocket motor design. Kerbal is a good way to learn that there are 2 ways of solving the problem of too much weight and not enough thrust: more rockets or more stages.