This might be a meta-meta question, but here is the idea:
- With 10-10k users on a site, no reputation is needed - everyone knows everyone else.
- With 10k-1m users on a site, reputation is the best way i've heard of to track how "useful" different people are to the site.
- With 1m-100m users on a site, does it still work as well?
As an example, on Wikipedia, which admittedly uses a very different model, once the site was viewed as canonical, it started being viewed as a target, instead of just a resource. If Stackexchange starts to get there, what changes would be needed? Similarly, over time, is there any idea about how to prevent older and less useful content from accumulating and poisoning the well? It is too easy to poison, and too hard to police.
- The number of past questions increases linearly with time, but the cost to organize them is very non-linear. (Just assuming constant numbers of users, over time the site could become less useful as a source because of decay.)
- The potential for spam increases, and the reward for well disguised spam increases. The cost of eliminating spam is constant, but the volume of spam can increase as a function of the number of users, and therefore the value to the spammers. (Because down-voting costs rep, and marking as spam is an action requiring moderators.)
- The value of becoming a trusted user increase with size, and the cost is constant - So we should expect to see more users trying to get to high reputation in order to abuse the system. (The cost of getting to a given reputation level, in terms of time invested is fixed, the effective reward for doing so, in terms of power and influence, scales with the site's popularity and visibility.)
These are just some initial thoughts, but I wanted to know if there was discussion about how to avoid becoming victims of the success of the site. Is this something that has already been discussed, and I was unable to find the discussion?
Edit: To reiterate: Are there things that can be done to make the site less vulnerable to these concerns as it continues to grow. Many of these items are not currently problems, but the problems can grow exponentially, and the solutions grow linearly with the size of the user base.