I'm still not sure why we don't regulate companies like facebook like we did the rail industry. Force facebook and other social media companies to develop an open API and standard and guarantee interoparibility, akin to other federalized networks that already exist.
This takes the biggest anti-competitive aspect of facebook out, the network and walled garden effect they have due to their sheer size.
It will mean that companies like Signal have much greater chance to compete with whatsapp, it will reward whoever provides the best service to their users, and it is relatively light and uncomplicated regulation.