One thing the current company oftentime couldn't offer is a change of scope and focus, bigger companies tend to be better since they have many more teams that work on very different projects.

Another observation I had is that the upwards mobility is easier in between companies than within the company. The sad truth is, most companies only acknowledge your importance when they are about to lose you. If they consider you are comfortable in your position, they have no incentive to promote you. So assessing yourself against the job market periodically is a logical and practical way to keep your career path in check, regardless of your company.