It requires a VM (as noted below) or an old phone you no longer use. I wasn't actively using my Nexus 5 anymore anyways, and this is a better use for it :p

And yeah, it's be forwarded and re-sent through the phone/VM. But this is the best trade-off I've found for dealing with people that refuse to leave WhatsApp. I look accommodating and don't just cut out someone I presumably need to care about, but also limit how much data FB gets.

And while I haven't tested this, I'm now curious how always having WhatsApp Web active affects my "Last Seen" time...