You cannot compare billion dollars established a company, existing years ago, to today's SaaS startup. It is like comparing solutions form 2010 car to 2016 car. Web market changes fast.
That doesn't mean anything.
You can charge more for more users, there's nothing wrong with that model. The more resources you require, the more you pay.
I used to work at NetSuite and this is exactly how we did it, the real cost (after any consulting) is the cost of users.
We exited to Oracle for 9billion.