I much prefer top-down flow in any programming language and adopt the modular approach with the main program logic as the simplest control flow possible.

Each time this debate comes up there is no proof that the Shell inward redirect is faster than using cat. I can't see why the Posix folks don't make cat a Shell built-in rather than try to retire the command.

Have you read the "Useful uses of cat" collection from the excellent Mascheck site:
Useful use of cat(1)
That list includes a contribution from a certain Chris F.A. Johnson !
An enhanced version of the "convert file contents into arguments" contribution came up on unix.com yesterday.