Because of network effects the understanding of a monopoly has to grow with changing technology.
The fundamental problem is that it wouldn't even be desireable to split up many of the new social media and internet technologies because that would reduce the quality for everyone, increase costs to support as a business and increase environmental damage from duplicating server storage and power consumption.
What we need is to turn them into public utilities that have significant democratic input by their own workforce (the experts and enthusiasts) and the users (the billions of people who actually create the value for the thing).