VMWare does not support --parallel

I am not sure if this is a bug or just undocumented, but neither VMWare Fusion or VMWare workstation support the `--parallel` flag. We have received a few support tickets around this /cc @mitchellh.
@mitchellh is this document wrong then? https://github.com/mitchellh/vagrant/blob/sethvargo/document_parallel/website/www/source/blog/2013-12-09-vagrant-1-4.html.markdown#L117

> Running multiple "vagrant up" commands in parallel with VirtualBox is now safe. This is a boon for CI or automated environments.

Or is that talking about something else? That sentence is what led me to believe it is not.