Also hacked clients, like metro, have macros which is similar. Just type the commands you want and assign it to a key. Or grab yourself a macro. So you can easily go home.

The underlying point of skyblock is to survive. Yes fall deaths are sometimes not your fault but its up to you to never keep valuables in your inventory. Make sure you afk safely. Don't use 1.9.
So to implement a plugin that prevents deaths by not allowing you to enter the void... it does really take some of the challenge out.
Water at your spawn and a hotkey is good enough.