That's... just how you run a sustainable business. As you grow, you simply can't support the small guys with their legacy shit and corner cases. Every service business does this. You have to.
I've actually heard the opposite. Once you have a few large enterprise customers who bring in disproportionate amount of your revenue, you end up having to service their bespoke needs and corner cases, at the risk of losing them as customers. So the product ends up inviting a lot of complexity.
Having worked at a startup that was beholden to a very large client in the space. I too can agree that this is more like what actually happens. The tail wags the dog.
Exactly. You support 5 big ones or die trying to support 100 little ones.