Yes that's kind of the point. It's actively dishonest to attribute the difference to web3 vs web2. If OpenSea thought they could get away with taking a 45% commission they would do it.
OpenSea does have some advantages of network effects and has been able to mostly fend off LooksRare, despite charging a 2.5% vs LR's 2% marketplace fee. There's no way they could have done so if they charged 25% and users could save 23% on every transaction by moving to LooksRare. Similarly, if Airbnb were "open database" and anybody on the internet could build a competitor that used the same data set, there's no way they could take the high fees they currently do. They don't have to, since they're web2, though. All the data about hosts, guests and ratings is in their database and they don't have to share it with incumbents.
Social media companies would feel this, too. A huge part of their lock-in is that they own the social graph. It would be a very different situation if that data were on-chain and anyone who wanted to could write a different front-end to surface the same data (some cloning the look and feel closely and other choosing to surface different subsets of the data in different ways).
[0] https://medium.com/bloated-mvp/why-web3s-shared-data-across-...
All of Chris Dixon's tweets you embedded in your Medium post are correct.
Data stored on the Ethereum blockchain and similar ones is public and anyone can build against that data. This is due to the fact that the blockchain is a shared public database. If Twitter's account and tweet data were on-chain, anybody would be able to create a Twitter client that surfaced the social graph and related data in whatever UI they chose and Twitter could not stop it.
If you're technically minded, try building a few throwaway Twitter projects on Ethereum testnet (or Solana, or Avalanche, etc) and get a feel for how it works!
Make an on-chain Twitter clone (e.g., like Bitclout/DeSo), where 3rd parties can't make their own clients for interacting with the same social graph.
Send me a link to the repo and I'll be happy to discuss further and even share any surprises or lessons learned from it.
[0] https://medium.com/bloated-mvp/why-web3s-shared-data-across-...
TBH, it looks like you have a huge axe to grind but don't understand the subject very well. That's why I suggested that you try actually building some things using web3 (which is an eth library)!
It will give you a better mental model of how it works. That will definitely improve your ability to write about web3. Imagining hypothetical apps falls far short of just building a prototype.
Thinking through a topic has a type signature. The required type is "example scenario of your point". You are making points that are vacuous, points that have no example scenarios. It's a problem that can be caught in type checking.