Because neither of those elements have any bearing on maintainability beyond what is customary for a Rails application. The wonders of pjax is that it doesn't require you to change your application style and structure at all, so it has zero impact on maintainability.
The granular caching scheme is similarly just a fragment caching setup using key-based expiration. Nothing new here, just that we used it to full effect.
So you're free to claim that writing Ruby on Rails applications are somehow inherently hard to maintain, but you'd be fighting against 8+ years of evidence to the contrary. Versus, you know, a very short amount of comparable evidence for JavaScript MVC applications based on current, recent frameworks.
The granular caching scheme is similarly just a fragment caching setup using key-based expiration. Nothing new here, just that we used it to full effect.
So you're free to claim that writing Ruby on Rails applications are somehow inherently hard to maintain, but you'd be fighting against 8+ years of evidence to the contrary. Versus, you know, a very short amount of comparable evidence for JavaScript MVC applications based on current, recent frameworks.