One last thing you forgot to mention. zsh is rarely installed on remote hosts. bash is everywhere.
This is a game changer in my case where I can simply download my configuration, load it in the current session and start using all my scripts, aliases on a remote host in less than a minute.
Don't get me wrong, I'm using zsh for personal stuff and computers I have complete control over. But, if I have to write a script, I'll make sure it works with Bash first.
"I can simply download my configuration, load it in the current session and start using all my scripts, aliases on a remote host in less than a minute"
Nothing's stopping you from uploading zsh itself to your remote hosts along with your .zshrc.
Or just use the package manager to install zsh on those machines. On any modern Linux distro it's as easy as typing something like "emerge zsh" or "apt-get install zsh".
This is a game changer in my case where I can simply download my configuration, load it in the current session and start using all my scripts, aliases on a remote host in less than a minute.
Don't get me wrong, I'm using zsh for personal stuff and computers I have complete control over. But, if I have to write a script, I'll make sure it works with Bash first.