People who don't make an investment in STEEM (however small it may be) don't stay for longer than 2-6 months, because they get zero visibility ragardless of how good their content or comments are.
I am talking about established accounts, who have been around for a while or at least invested a few hundred bucks.
But you are right. From an accounts perspective, most people will not be able to contribute anything other than their small upvote.