I still believe that PHP is the best language for the web for the majority of programmers; it quite possibly has the best documentation and examples of any language like a DSL for the web! [...] So why is Scala easier?

The first reason he suggests is that Scala, unlike PHP makes it simpler to handle concurrency issues and makes it to where partial functions and mutable/immutable types all play well together. He compares some of the skills a PHP developer might have to have to reproduce the features that Scala comes built in with (a "resume" of 13 lines as compared to one with 5).

It really is a grind to overcome that first 4-6 months but if you need scale I would recommend taking the haul. It will change how you think about problems forever.