I think the fact that you could make so much steem just by already having a lot seems strange to me - it should be designed to reward quality and discourage just gaming for profit.

Yes, it is strange, nut it is about having value directly between creator and consumer. Normally, this value is only available to a centralized authority, for example Facebook. Stakeholders own the network and help stabilize the platform, similarly to centralized platforms. The difference is, pretty much every creator could earn with a little effort, whereas on the others, very, very few can - and those who earn highly are chosen to earn highly by the platform - not the community.