incorrect claim: Bash is powerful and always available

[matu3ba]

On embedded systems one might want to use ash for size reduction. Or dash for performance.
So this is an incorrect statement and one should recommend the non-bad parts of POSIX shell like these and warn about [ ] if clauses.

This statement is also incorrect for various CIs for Windows (jenkins, github actions, etc).

Finally, and most important, bash is no generalized programming language and like all shells a hacky system interface to simplify job control, human increase input speed, provide interactivity and to administrate the system.
Bash and shells are neither designed nor able to be used as library, nor extended (shell language is slow, failure handling is not robust or very verbose).