That comes down to the ability to say no (or at least "not yet"). I have seen lots of startups that land a few mid or big clients and lose the plot by serving every throwaway request the client makes. Doing this slowly turns your product into a bespoke solution not fit for others. There needs to be constant tension between the product goals and its application, and holding that line will always, always annoy a sizeable swath of users.

Apple famously ignored users on lots of fronts: can't manually add RAM, mouse has 1 button, etc. They didn't serve one type of user specifically so they could appeal to a larger market. You can't serve everyone.