They are still quite powerful for doing Objective-C and Swift related development, the developer audience Apple cares about.
Google, Tesla, Facebook, and tens of thousands of other businesses purchased the 2012-2015 rMBP form factor for a reason - its a great laptop. The number of people who use the laptop that do not code in Swift far outnumber the number who do code Swift.
Still, a greater number use Macbooks casually, and I'm sure the standard Macbooks are great for home and recreational use. To clarify, my focus is on a professional use found in a standard business setting.