As the company grows and becomes more established, the higher level roles get filled or become "crowded" and upward mobility becomes harder. More competition from peers, higher bars are set, there can only be so many managers, etc. With less opportunities for promotions the base salaries need to start matching larger more well established companies or I'm afraid there will be more "churn" in employees. When quarterly financial updates tell us how much revenue is growing each quarter and only so many new employees join during that time I wonder where all the money is actually going. Transparency on what the company is spending on might help alleviate this.