I think experimentation is one of them. being able to easily break backwards APIs to try new things in each version may not be nice for large scale projects. It's nice to try new things, but it can be a maintenance effort in terms of sustainability. and such projects are usually used for a large project so core development can go a certain line. (like google products for angular, facebook products for react). it doesn't seem to apply to this svelte. It is debatable, of course, that it is a negative thing. But I think it's a shortcoming.