I'd like to understand why are Senior and Lead Engineer roles for Front-End teams In-Person interviews specifically inclined toward Rapid Prototyping off-late?

1. Consider fixer.io API to build a Currency Exchange Rates app, either web-based or mobile-app, within a span of 2 hours.
2. How about vertically Expandable-Collapsible feature for each horizontally scrolling Movie-Collection row in Netflix, upon tapping the name of the Collection, within a span of 45 mins?
3. Build a basic app, with two to three transitioning screens that mimics a Vending Machine in about 1 to 1.5 hours.
   Production Ready Quality code following SOLID principles with comments and Unit-tests is High Priority for the job and the company.
   Rightly said by Mr Satya Nadella in 'Hit Refresh', Software Development sucks the Soul of the Engineers.