Sorry to nitpick but that isn't scaling. Unless I can add double the number of machines and double or almost double the capability, and keep doing so to thousands of machine your application doesn't scale.
In the case of web applications all tend to scale equally well as you can just add another web server. Its the database that causes the scale issues.
Scaling vertically is still a valid strategy, and is scaling. Not every company needs to be able to scale to the moon, and if they don't, it's a poor use of time to focus too much on architecting for scalability.
With a lightweight PHP framework and a sensibly written app, you can stick to one machine for much longer than you can with Rails, and after that, it will require a fraction of the number of app servers. Beyond that, app processing time is generally much lower without all of that cruft, so you don't need to do as much caching, etc. to get a snappy webpage.
In the case of web applications all tend to scale equally well as you can just add another web server. Its the database that causes the scale issues.