Sounds like nonsense to me. If I write something in Django, I can let the forms be auto-generated to whatever degree I like. If I do it as a SPA, I essentially

Sounds like nonsense to me. If I write something in Django, I can let the forms be auto-generated to whatever degree I like. If I do it as a SPA, I essentially need to twice as much work, as I have to write a backend to serve and consume JSON and a frontend to display and interact with it. Then you have got the nightmare of debugging the mess.