I teach shell scripting. Cat invocations are cheap and help learners understand and keep clear where input is coming from, and where it is going. There are no awards or benefits to reducing the number of lines, commands invoked, or finding the shortest possible way to perform a task in a script. There are plenty of detriments to reading and understanding though when we try to obfuscate this to save 1ms of execution time on a script that is going to execute near instantaneously anyways.
I 100% agree with you. My only defense of OP is that `<` is something tends to be forgotten. Like everyone else in this thread I go to `cat` first for things like this. But sometimes I forget that even `<` exists, and the callout is a nice reminder.
In short, I straight up don't care.