It would definitely prevent abuse, but still give people somewhat of a reason to vote for you.
I think that 50% on all main level posts is a fair compromise. This helps support the sustainability by growing the secondary accounts directly and they only post like once a week or less anyways. it's a really small amount of rewards at 50% that we are talking about, but it helps keep the program strong.
A side note, I'd love for a few larger account holders to start a new account without telling anyone this is what they are doing. They can use all their knowledge of steem, but none of their contacts to try and grow their account. After 3 months share with everyone how much effort they put in and the results of that effort. Then be honest how much of their success was due to knowledge of the platform. Even with this knowledge I think most would be shocked at how hard it really is to start off.
Programs like SBI are really helpful in keeping smaller accounts active and growing. Gut it and we will really have issues around here IMO.