There's also very little friction to prevent centralization. With physical goods, there might be geographic/logistical reasons why a dominant player can't easily be competitive in every market, but this largely isn't true of tech.
And given the short time-frame needed to bring a software product to market, how possible is it really for a small player to compete with any of the software giants? Even if you come up with something really innovative, how likely is it that your product can't be replicated by an organization with infinite resources?
Historically, this is probably one of the easiest times for a small player to compete with the giants. Is it really harder to compete with big tech than it was with Rockefeller's Standard Oil, Carnegie's steel industry, Vanderbilt's railroads, AT&T's national phone network?
It's much easier to compete against tech and we have evidence as small players like TikTok, and even Snapchat have done it successfully.
I saw a paper once saying that in any market where the top four competitors controlled more than 60% of the market, they'd act as a de-facto cartel. (I wish I could find it again).
Also network effects. Facebook and Twitter aren't king because of their scalability, they're king because you use Facebook/Twitter to connect with the two billion people who are already on Facebook/Twitter. Not even Google managed to sustain a competitor to Facebook.
In that sense, we're doomed to give ourselves 1984 unless we consciously and continuously fight everyday to not slip into a dystopia.