This just shows the command line was badly designed to begin with.

If CLI programs received already-opened file handles instead of pathname strings, most programs would have no need to have the concept of a "current directory" at all. It could be something purely internal to the command-line shell.

It would also be more fitting for a capability-based OS instead of one where every program has an ambient permission to access anything in the whole file system.

So am I, as a terminal user, supposed to track file handles now?

CLI programs might be used by an actual human, not necessarily called by a script.

UNIX/Linux already has a compromise here with stdin/stdout/stderr, the convention that those are fds 0, 1, and 2, and stream redirection in shells. You can already redirect raw fds in bash on linux, that's exactly what "something > something.stdout.txt 2> something.stderr.txt" does.