> one can still say that in syntax similarity, Crystal is a 'faster and memory efficient Ruby with static types'

Actually they don't even share the same syntax for declaring getters and setters. Honestly speaking I think people really only think of Crystal as "faster Ruby with static types" because they've mostly been exposed to C-style languages so anything that doesn't look like C just blurs together as "the same".

(Obviously Crystal is heavily inspired by Ruby, but there's a huge difference between "heavily inspired by" and "an implementation of".)