How do you force a split when one part (Whatsapp) may not have enough revenue to sustain itself?
Your phrasing obviously comes with the interpretation that if a split-up would bankrupt a part, it shouldn't be done. Why should this be taken into consideration?
Secondly. It has value. A different party could invest and keep it going. Why is it important that it sustains itself?
Of course, if you just wanted to punish facebook by destroying shareholder value, or you're certain WhatsApp users will move to an FB competitor rather than to FB itself, you might not care if WhatsApp stays in business post-breakup.
My impression of the situation is that Facebook bought WhatsApp for its data and user-base; not because it was competition.
What _will_ happen is that other free services will pop up and be used, and some users will migrate to those. Which is a good thing. We'll have actual competition on the field instead of a single dominant player.
That the Signal Foundation is now basically funded by interest earned on money made from that very WhatsApp sale is quite poetic.
https://www.google.com/amp/s/www.wired.com/story/signal-foun...