Every UX designer is standing there with their heating element in the ocean wondering why the water around it doesn't boil.
This is a fundamental tension I have experienced in software businesses for my entire career. Sometimes the UX designer is just a business person, but regardless of their title, they don't understand this simple principle of building software products: the longer a product or feature lives only within your own computer or your own organization, the less chance it has of living in the wild. Software products really are like babies: they are only meant to gestate for a specific amount of time; and for software, that time is much closer to nine days than it is nine months.
This is based on another simple principle that was best described by Field Marshal Helmuth von Moltke the Elder in 1871:
No plan of operations extends with any certainty beyond the first contact with the main hostile force.
The simple fact is: one does not know how to best build a particular piece of software to best meet the needs of its users. One must iterate based on actual use by actual users of that software, and actual users can't use software that hasn't been released.
It takes both humility and courage to release software. The alternative is piles of unused designs and code, dead because it was never validated before it was built.