People who started after Rails was released don't see it because they haven't seen how it was done before. But it's incredible how many conventions DHH created with rails that have since entered the basic repertoire of all web frameworks: migrations, its take on MVC, :belongs_to, the router DSL, the asset pipeline, generators – while you can probably find prior art for all of them somewhere, it's the implementation in Rails that, 10 years later, is still the blueprint for new frameworks.
Rails was also the best teaching tool ever invented in the space. Code quality was atrocious, people were reinventing "clever" solutions for every project, testing was probably rare (I never saw it, but it must have been around, right?) I distinctly remember a templating system that turn .xls into a perl script that would write php. If you changed projects, you'd usually be greeted by a directory tree 8 levels deep with the main config.php in /[..]/tmp-2008_b, along with config.inc, main.html.php.old and construction.gif~2.
(Not that Phoenix doesn't add lots of refinements that make it a pleasure to use)