While seniority on the platform definitely leads to more social clout (and more rewards from the reward pool), any newbie can have more voting power than a low investment old-head. All it requires is to have more capital. Jeff Bezos could come in right now and become one of the largest holders of Hive if he wanted. And with that we'd all become a lot richer (obviously), but our voting power remains the same. Bezos would gain dramatic powers to influence the direction in which the blockchain grows, and there would be people who court him to try and get large upvotes from him.