Steemit is a social experiment where everyone can choose to do whatever they wish with their stake. So it's an arena where, proportionate to the amount of SP one holds, one can manifest their concept of what Steemit is.

So obviously the most influential will be the mega-whales, and to that extent you are correct because some of them do as you stated. However, many of them also give away huge amounts of STEEM through their upvote to those holding small amounts of stake. Whatever Steemit, Inc. chooses to do with their massive holdings is quite impactful as well. Same with Hive account@dan and Hive account@ned, etc.

Overall, I have seen many with a pessimistic view of Steemit continually power down and cash out, and that is very good for the economy. We will see what happens, but I expect STEEM will be worth anywhere from $15 to $100 by the end of 2018. This, however, will not come to pass if people use Steemit in the method you are advocating.

Since most people have a profit-minded approach and cannot grasp why anyone would possibly want to manifest a gift economy, you may be correct. But again, it depends on what people who have an active stake in the platform do, so anyone who powers down and cashes out will have a very limited influence on its continuing evolution.

The only exception I can think of is someone who has widespread influence and support of whales, such as Hive account@papa-pepper, Hive account@sweetssj, etc. They have organic influence which will likely persist even if they power down.