> What power do big tech companies have

Aftermarket control, for one. You buy an Android/iPhone or Mac/Windows device and get a "free" OS along with it. Then, your attention subsidizes the device through advertising, bundled services and cartel-style anti-competitive price fixing. OEMs have no motivation not to harm the market in this way, and users aren't entitled to a solution besides deluding themselves into thinking the grass really is greener on the other side.

What power did Microsoft wield against Netscape? They could alter the deal, and make Netscape pray it wasn't altered further.