well steem only really does that by running blocks every few seconds - which can be problematic because it would take a number of blocks before there's a level of cohesion among all nodes.

it's really not very different to bitcoin/litecoin/vertcoin storing transactions in the mempool until they get picked up properly by the miners.

Lightning network is changing the game by processing more transactions off the chain, which more or less provides an infinite level of scalability.

and whilst we're testing transactional limits, we're also processing a lot more non financial transactions - and as the steem blockchain grows, so will the non financial transactions. For instance, we can't be sure how well the blockchain will handle Facebook levels of "transactions".