but without HBD or SBD

HBD and SBD have always been there, so neither Hive nor Steem have ever worked this way

since you earn returns on powered up coin, you usually are able to offset the inflation

You are pointing out another way that you don't know your future share of the percentage of the governance. Even if you "usually" can offset inflation, you can't be sure that will always be the case. Apart from the possibilty that the earning mechanism might change (as it has multiple times), earnings might become more competitive in some way and you find that you are no longer able to keep up, or don't want to continue to invest the effort to do so.

The only way you could know your share would be with a fixed supply of governance tokens and Steem and Hive have never been anything like that.