You have exactly the same mental image if you start a pipeline in the right way, with a file redirection: "<input_file cmd1 | cmd2 | cmd3 ...".

This adds the joy of doing only what is really needed, without extraneous effort.

Moreover, in this way the start of a pipeline becomes symmetrical to its end, which frequently is an output redirection.

same I just like monads lol. cat + pipe feels purer and has lower mental load for me, which dominates the efficiency of spawning an extra process for, typically, a few microseconds.