Naming things once

How is x = %i[a b c] better than x = [:a, :b, :c]? I find these kinds of shortcuts available in Ruby, and exploited to the maximum in Rails (et al), a severe detriment to understanding and exploring the code. Thankfully, JetBrain's RubyMine is almost always successful handling these pointless alternative codings. Ruby & Rails: Preventing successful grep-ing since forever.

Update: This is a somewhat related discussion on Hacker News, Greppability is an underrated code metric.