One of the best positions to be in in an open ecosystem is an optional but central complement to the ecosystem.

This is especially true if you have network effects that cause your quality to go up with more users.

Users are willing to use you even when you've grown big, because you don't have undue formal leverage.

You must actively compete on quality to maintain your perch.

But because of the network effects, it gets harder and harder for others to compete.

The result is you've earned the right to be the king of an important hill.