It’s not “no other option”, they can switch to Bash but it’s an old version, or they could install a newer version with Homebrew or similar. But none of those steps should be taken by someone just starting.

The point is precisely that the OP likely has no idea what their shell is. I wasn’t lobbying a criticism, but a correction so they are aware.

Regarding the example guide, I do think it’s not a great one for total beginners. someone with interest in learning the Terminal should be given an interesting resource that let’s them play a bit with commands and understand what it’s about before drowning them in theory and technical information.