As a Senior Programmer, I have noticed that culture falls off at about 50 employees. I’m not sure if that’s because it’s the Dunbar Number, or if it’s a self fulfilling prophecy by VCs. (I was actually told by one who explained his rapid hiring as “There are some standard formulas. It’s not rocket science, it’s just math.“)
Seriously, though, it is 10x as much effort to make something that “mostly” works work WELL. and after that its another 3x work to make it Truly Production Ready. If management doesn’t understand this fact, almost no one will take it upon themselves to carry the ball all the way across the field. Cruft accumulates, everyone tells management/themselves what they want to hear.
In short, a lot people know why this happens, but few want the real answers.