This feature is a bit different as it allows you for example to crosspost the work of a poet you find into a poetry community they didn't know existed - and reward them. It is pretty powerful.
I agree, and I can see how it can be used altruistically to boost a little known, or new, steemian's content to get more eyes on. Also, to reward them more with any autovotes you may have o your account.
As you've pointed out concisely in this post, it is a double edged sword as to people using it to abuse the rewards system... but I guess that's what free downvotes are for ;-)
Things are very interesting on steem at the moment, and I'm sure the peeps like @jarvie at @steempeak will figure out how to allow for posts to be submitted to more than one community soon.
I'm currently in the planning stages of possibly setting up a community myself.