I consider them harmful for beginners who need to start working on non trivial production code.
Multiple apps are definitely good for the admin but what I was advocating isn't 100% avoidance of apps but to avoid creating apps for every tiny feature.
Personally, I like my databases to be designed for longevity and avoid couple code to my data. Code can die at any point in time but data is an asset that needs to live for as long as the company is in operation.
> beginners who need to start working on non trivial production code.
If you're a beginner dropped into a non-trivial production codebase your best bet is to follow existing conventions until you gain enough experience to be able to evaluate such advice and consider it against your projects' and business' requirements.
Multiple apps are definitely good for the admin but what I was advocating isn't 100% avoidance of apps but to avoid creating apps for every tiny feature.
Personally, I like my databases to be designed for longevity and avoid couple code to my data. Code can die at any point in time but data is an asset that needs to live for as long as the company is in operation.