Funny you have to pick all 30 year old examples.

We have been running almost entirely Windows and Mac for over 20 years (at least in consumer land).

We have been running mostly Intel and nVidia for over 20 years.

We have been running mostly Chrome and maybe 2 others for 10 years.

We have 1 comprehensive social network (FB/Insta) for over 10 years.

We have 3/4 major internet providers and 4 wireless carriers - forever.

We have essentially 1 Search Engine.

We have 2 smartphone platforms for over 12 years.

... when there are 'new markets to be exploited' or a fundamental shift in a market (ie feature phones to smartphones) - new entrants have a chance, but outside of that, they don't as incumbents win relatively easily unless they get lazy.

Each of the major players above has been able to leverage their market power into domination.

IP is one of the few vectors of power for smaller companies (often the only vector) that stop these behemoths from wiping them out. Sadly, depending on the scenario, there are often few material IP protections to be had.

Of course, 20 years ago there were no smartphone platforms at all, no social networks, Internet Explorer was the dominant browser, Google was an upstart competing with search "portals" like Yahoo, a 3dfx Voodoo card was the hot thing to have, Apple was nearly dead, and Amazon was a place to buy books and CDs.

At the time people thought Microsoft was so dominant that most of the innovations of the past 20 years could not have happened, because Microsoft was a behemoth that would simply take over any competitors. But they lost on search, phones, browsers, etc.

I don't really see how it's different this time around. There is currently no company as dominant over the entire industry as Microsoft was in 2000, or as dominant as IBM was in 1980.