I often agree with this sentiment, but I think the big difference is various other things that would be very difficult to implement that you get for free when various parts of your system can rely on certain behaviors from other parts. For instance filtering, sorting,loading related data, providing input to computed properties, the list goes on and on. Using Ash with AshJsonApi or AshGraphql gives you all of that stuff for free.

If it were just the matter of putting a “skin” over something that already works I’d wholeheartedly agree, but the pros ultimately outweigh the cons when you can use a truly integrated stack instead of slapping a bunch of libraries together, or hand-writing everything yourself.

You can do things your way you can write your own standard controllers and call into ash resources and build all that stuff yourself if you want, even if you’re using Ash. AshJsonApi is just one extension of many that we provide, and that extension has a bunch of opinions about building a particular type of API.