At the moment these companies are acting more like viruses, infecting and feeding off smaller companies to stay alive, and often killing them to reduce competition.
I know many people upon reading that would say "what about my payout for the hard work I put into my startup". However, I feel like this culture of selling once you are successful only exists because once you are big enough to become a target, the prospect of continuing to fight against one of these giant monopoly giant-tech-monoliths is dauntingly impossible. If mergers were banned in the first place it would be much smoother sailing all the way to the top.
Then again I've never experienced a startup so I probably have no idea what I'm talking about.