What do you consider a better alternative? A lot of people love to hate on HTM+CSS, but it's actually fairly powerful. I've been trying out a lot of native UI toolkits, and they're all as quirky and confusing as web tech. I'd agree that there's tons of room for improvement, but any UI tookit will need to make certain tradeoffs and deal with complex layouts and compositions.

Flexbox and grid help a lot with app-style layout.