Which is why 25-50% of all whale Steem Power would need to be delegated to small curators (on 30, 90 or 120 day periods) in order to spread out the work of curating quality content.
If all the large sp holders prefer immediate profit than platform performance, then a whitelist is the only other ethical solution I can think of.
If you are okay with spam winning the day, then, by all means just keep doing everything as is now and await a HF magical unicorn to save the day.