But for most people without the large platforms and tooling of those megacorps the internet is mostly useless. Where would they even start without Google search?

And people come to the internet to communicate and form groups, having a gazillion website fundamentally does nothing for this goal.

Even today we can see the attempt at a decentralized network with things like Mastodon but it is never going to take in any meaningful manner, because the centralisation aspect is exactly what people are looking for. It's kind of the forums of old roman cities. You need one big one to be able to accept everyone, having a bunch of small ones spread out in the city is not only useless but also completely counterproductive.

The only real problem with the megacorps is that they figured out better and faster than the hopeless idealists what people would actually want/need. So instead of having things that could be interoperable public utilities with a focus on standards, we have the wild west of commercial competition and monetary exploitation with ads.

All of this happened/exist because the internet is a naive and lackluster protocol. Without the massive commercial investment of those companies, it would largely be useless. The reason it took off is basically only because it was free, not for real technical merit (the same thing for Linux).