As a cross-poster myself, I agree to your proposal, cross-post is indeed a good way to share some content with several more or less specialized communities. It is indeed a pity that the incentive to cross-post is low if such curation is not rewarded.
I also agree that remembering the 6 digit names for the communities adds friction to sharing.
I mean this change won't "incentivize" it with rewards, which I think is good for it to remain that way, similar to reblogs don't earn the reblogger rewards. All you do with reblog's is just altrustically help the author you reblog the post of get more attention/rewards if you have a good amount of followers who frequent your reblogs and like your history of sharing. Sure maybe they may thank you with an upvote on your comment on the reblogged post for having introduced them to the content they really liked (I some times do) or upvote your recent post as thanks, but not directly monetize cross-posts or reblogs.
What this does is simply not dis-incentivize people from doing so and autovoters, whether we like them or not are a norm on this blockchain and won't go away soon and most authors are aware of this and many strive to receive some kind of autovoting support over time for their effort and consistency. This simply means that the authors won't be afraid to lose that support because their cross-posts are causing their supported to lose out on returns.
Thanks for the clarification, it much clearer now 👍