Combine multiple fields in one easy-to-fill field
Designing More Efficient Forms: Structure, Inputs, Labels and Actions
Nick Babich

I agree with the concept, it’s just a shame that in your example is Date of birth, using a date picker (which is great for correlating days with dates, fairly decent for months and pretty terrible for years). By using a date picker you’re putting a lot of emphasis on the day of the week which for date of birth is totally irrelevant. Who cares if you were born on a Monday? Scrolling back more than 10 years is also a mega pain in the ass on most mobile operating systems :(