I'm not going to go threw the history of computing and argue ever point. The simple fact is your statement was way to broad and you know it.

And yes I know about IBM, I have heard of them before.

> Its a very strange view: If an entity is not dominating 100% all related markets its not a monopoly.

Where to draw lines in what is considered a market and a monopoly is always questionable. But its besides the points, because your statement was not, monopolies sometimes exist in the broader computer industry. Your statement was something inherent in 'Digital tech' was somehow extremely prone to monopolies. And I don't think that view holds water. Different market segments had different periods of consolidation and centralization.

Yes, IBM and Microsoft were sued in anti-trust cases, but in both cases they didn't lost their dominate positions because of those anti-trust cases.