Collecting Coins By Date, Why?

In particular, a lot of people probably started out by collecting from circulation, which (especially pre-state quarters) naturally lends itself to date sets.
Also, type sets usually imply a far longer time period, which can be harder for a beginning collector to wrap their head around.

I started as a date collector myself, but as I shifted my focus to world coins and/or older coins, I naturally graduated to collecting by type - there were just way too many dates to bother with.
(Perhaps fortunately for my budget - though, in retrospect, very unfortunately for my theoretical reselling ability - this shift happened before I started actively buying coins, so I never had much, if any, interest in key dates.)