Obviously you mixed up capacity with scalability.
Scalalbility does not particularly care whether you have high traffic or 1000 employees. Scalability is about: whether you can easily configure the system to have the right capacity that you required, so that it uses the right amount of resources to support this capacity. For example, if you only have 1000 employees now, the system can be configured to use the right amount of CPU cycles, memories etc. to support this capacity. What if your company will double its size in 3 years, fine, we reconfigure the system and that process will be painless, so that it can support the traffic for 2000 employees, and probably use 110% more resources. Now you want to open up a sub-company that only has 100 employees with some low end computers, fine, we install a set of the software, and configure it to support only 100 employees, and the low end boxes fit greatly.
This is scalability.