Ok, yes I see. 
I'm wondering if there is a way to avoid having to store the entire blockchain on a node. There are probably many problems with this idea. But I can see blockchains growing very large over time. I'm sure the steem or other blockchains have figured this problem out or are working on it. 
Now that I think about it, my idea of not storing the entire blockchain, violates one of the fundamental ideas of blockchains, trust. But as you said, you also have that problem when using someone else's API to the blockchain. 
Sorry, just thinking out loud here.