Currently UX designers are often like chefs who work by drawing pictures of food and writing down conceptual recipes. When they've created a beautiful menu this way, they're surprised to find out that their recipes can't actually be made using the cooking equipment available, and some of the ingredients don't even exist. You're not going to run a Michelin-rated restaurant like that.
The industry desperately needs better UI development tools. To continue my (already strained) food analogy... Right now we are still in a "hunter-gatherer" stage where everyone does their own thing, teams are foraging and hunting, and occasionally they stumble on something great. Consistent UX will require an "agricultural revolution", a systematic production innovation that makes the essential pieces more understandable and repeatable in isolation.