Could one build a "Stack Exchange" like information structure or process over Ethereum? Could the "Stack Exchange" team use Ethereum to build a new and improved information learning structure? As it is people could make multiple accounts(or share one account) to trick the "Stack Exchange" process just as much as they could do the same to trick the Ethereum system. But, using Ethereum fuel could someone make a "Stack Exchange" 'like' Ethereum based program to infuse true value into actions of contributing individuals?
I see how this question maybe a duplicate, but I'll give a take on it since the question asks about "structure" instead of "site".
Ethereum is a platform for decentralized applications, with a focus on global consensus (agreement) of computation and logic. By itself, Ethereum is not designed to be a content platform.
In terms of structuring a "StackExchange-like" DApp on Ethereum, the general recommendation is to store data on other technologies such as Swarm and or IPFS. Hashes of the data is what would be stored on the blockchain, and the DApp would query the storage technology for the actual data, and then present it to the user.
What else could be stored on the blockchain? The logic for voting and the votes themselves could be stored on the blochain: the purpose would be secure, transparent voting where no administrators could override the number of votes, and vote totals could only be altered according to the rules and logic encoded in the smart contracts.
Storage directly on the blockchain is very expensive. Something you could do is store hashes of comments on the blockchain, along with votes, and store the comments themselves on IPFS or Swarm. It'd still be kind of expensive but might be feasible, especially once sharding is deployed.