To the user, your front-end is your product.
As much as I love thinking about UX, I dislike implementing it. Iterating over my back-end code brings me joy. Do the same with UX? Not so much. It’s tedious. It’s all about the sum of minimal tweaks. Each of which requires a lot of effort to feel right on many devices.
And there’s often no obvious finish line. I wonder how da Vinci knew when the Mona Lisa was done.