Looking at it another way, if everyone on Steemit decided to only upvote themselves, how soon would it be before the platform ground to a halt? The whales, dolphins etc getting richer and the poor minnows and redfish getting nowhere, swimming as fast as they could for $1 per 1000 self-upvotes?
That's why Steemit is alive. Cause there are people that invest their time and efforts in posting/commenting some really nice and interesting information. And I hope that we will have more and more such Steemians. This is one of the most important condition for Steemit community growth and health.
You're right. It's not just important, though, it's vital :)