Phoenix is awesome! I agree that performance is not everything. I would have to disagree with the quote
There are huge advantages that Crystal offers for those who embrace OOP, and not functional styles, I would say from my experience working with Crystal is that is almost a low level language with a high level API. Crystal was born out of an experiment to make Ruby faster, but soon the experiment took a different direction giving birth to the language.
Crystal is NOT Ruby it feels like and it looks like but it is nothing like Ruby; Type System, Null checks, Macros, Concurrency and the fact that is similar and feels like Ruby, makes Ruby developers feel at home, not afraid, and for people that complained about ruby not being fast, type checked, etc is the language that they have been waiting for. Crystal is faaster than Ruby with better memory management, and it sits almost on par with GO and yet there is no parallelism built in. It is true, Crystal not yet popular, not yet 100% complete but it is very promising.
Now Elixir, was beautifully design and developed, on top of the battled tested Erlang hard to compare to, almost not fair. Phoenix a framework to admire, beautiful docs, concepts and great community. Lets not forget that inspirations comes from everywhere. The same way Amber got some inspiration from Phoenix, the latter got from Rails (I guess this is how things evolves)
For those who care about speed I would consider the TechEmpower benchmarks of great importance since it has standardized bench-marking frameworks, consistently, with a thorough testing process, unbais to any language, with a rigorous PR review.
Let’s not judge for the cover of the book, when the true story lies within the pages.