Even if they had, doesn't mean it's a good idea to flood the product with changes, nor it's necessary that the market has the capacity to asborb and expand your sales, or that the existing customer base will appreciate it.
I think startups have an easier time for 2 reasons: They are innovating on the product side already, and probably were already capacity constrained for work on the top ideas. They also have a high proportion of tech debt which never bubbled to the top of effort vs reward (competing against product work) before but would still be valuable to fix. E.g. https://posthog.com/blog/sql-parser was on the HN frontpage a few months ago, and this work would never have happened in the before times
If it's easier for startups, it's for the same reason doing a "pivot" is easier: they usually don't have much of a product or revenue or customer base to begin with, they throw things out there and see what sticks.