I can think of two reasons.

1. There is more than one way to "skin a cat" legally but one way might be more efficient than another.

2. They don't want us to be responsible for having to remember even more mumbo jumbo.

I think this is a "technique" versus "procedure" type discussion. Best practices are techniques to get the job done but are not a required way of doing it whereas a procedure is a required way of doing it....see number 1 above!

Generally speaking, Delta has always given a wide range of latitude, where they can, on how you get the job done.

Denny