From knowing nothing to building a simple web app, PHP is faster.
If you already know RoR and have your dev machine and deployment environment all set up, then it's not hard to get a Rails app working. Rails has a significant advantage with the use of gems (and bundler, etc.) for easily adding complex features.
I still use PHP for my home projects most of the time because I haven't bothered to set up Rails on my VPS, so the effort it would take to do so just isn't worth it compared to how easily I can drop a PHP app in place. (I am using a framework in PHP too.)
But then, the author was talking about PaaS not setting up Ruby on a VPS. So in that case it's probably just about how comfortable the developer is with each language. I'm a bit more comfortable with PHP because I don't like debugging Ruby GEMs that use instance_eval black magic for DSLs and/or have to be inserted as Rack middleware. Not unless the project is large enough to make Ruby gems worth it.
(Eg. if I want good unit and integration testing. For home projects I rarely do integration testing. E.g. #2 was rack middle ware for REST API.)
I'd say you can get from zero to working app faster in Rails. You can get away with knowing no SQL, and not really grasping concepts like GET v. POST. A few scaffolds, Omniauth, and one of the Bootstrap gems, and you've got a decent app worthy of Show HN karma.
In PHP, you need to learn some HTML, some SQL, and general web concepts that Rails hides.
No, learning isn't bad. No, I don't think scaffolding is acceptable. I've used PHP since v3, and Rails for a couple of years, and many other languages since 1999, and I'm just trying to get into the beginner's head.
If you already know RoR and have your dev machine and deployment environment all set up, then it's not hard to get a Rails app working. Rails has a significant advantage with the use of gems (and bundler, etc.) for easily adding complex features.
I still use PHP for my home projects most of the time because I haven't bothered to set up Rails on my VPS, so the effort it would take to do so just isn't worth it compared to how easily I can drop a PHP app in place. (I am using a framework in PHP too.)
But then, the author was talking about PaaS not setting up Ruby on a VPS. So in that case it's probably just about how comfortable the developer is with each language. I'm a bit more comfortable with PHP because I don't like debugging Ruby GEMs that use instance_eval black magic for DSLs and/or have to be inserted as Rack middleware. Not unless the project is large enough to make Ruby gems worth it.
(Eg. if I want good unit and integration testing. For home projects I rarely do integration testing. E.g. #2 was rack middle ware for REST API.)