Yes, fair point but there are limitations.
1. That license comes from a centralized authority. This can (and will change) in the future. Licensing 50 years ago is radically different from today and licensing 50 years in the future will be radically different from today.
2. The fact that there is a license means there are some terms of service / restrictions -- otherwise why even have a license?
3. I'm not sure how the often the data dumps would occur but if they are not as real-time as possible that creates a flaw area (data can be changed). What happens if stackoverflow, goes back and changes/modifies some user data from 2 years ago Sure, when we reconcile old data dumps with new data dumps there will be a discrepancy, but who will be doing these checks all the time? Blockhain has nodes which secure the system so all data matches.
Why use something that comes with barriers when there is a better solution -- true decentralization.
And apart from data access, there is power in holding a part of the project itself -- the tokens that provide governance. You can be a day1 stackoverflow user and post every single day since then and yet have no say in the direction or decisions of its future. Why not truly decentralize the system and let the participants in the network also decide the direction of the product (including the original team as well).
Finally, there is a lot of transparency when it comes to using blockchain (contrary to popular belief). If the founder decides to move his tokens -- everyone can see it in real-time as all token movement is transparent on the blockchain, along with other benefits.
Overall, blockchain and decentralization brings more transparency, efficiency (but not always), and fairness.
The last 100 years has been an insane bull market for the middle man. From grocery stores (middleman between producer of food to consumer of foods), to Uber (middle man between driver and passenger), to Youtube (middleman on video content), to even storing money (banks). And they take a massive cut for providing that service, despite most of the value coming from the participants. Prior to this, everything was direct -- people went directly to the farmer, or driver, or held gold on their own. I believe we will head back in this direction, where the the "middleman" will become a decentralized entity and the "cut" will be passed right back to the participants.