This above means that in theory ones stake increases to counteract the loss of value over time. As I understand it?

Yes, but currently, even then you still lose out, because you're only gaining 15% of the total 100% inflation. Which is why so many people turned to bid-bots.

Can this statement above be correct because in order to post (authors) on steemit etc.
A user must have some steem vested and resource credits? Unless I am missing something?

You need a bare minimum of Steempower in order to create posts/comments.

Regarding your general point about author rewards:

People are writing on medium for free, without gaining anything. We need to stop thinking that authors are somehow entitled to their rewards.