Regarding SMT's

What is different about that from a points/rewards system?

This isn't likely going to convince anyone, but already the first difference is that it is on decentralized infrastructure, meaning that the token owner is bound by certain rules regarding the token itself. For example, they cannot arbitrarily remove tokens from one's wallet.

The other is the ability to layer a reward system analogous to Steem that can reward based on votes. The white paper outlines the vision in detail.

You can point to all the different token sites like https://palnet.io as an inkling for what it looks like now (splitting into individual communities, in a sense), but I think the vision goes beyond this.

STEEM vs STEEM Power

The main difference I would point out is that SP gives you more influence over the reward pool, governance (witness voting), as well as other perks like getting part of inflation. In exchange, you lock an amount of STEEM up.

Identity

The way I think of this from an extremely high level is that we are building up a parallel economic system. The rewards encourages participants, as well as a system where SP holders can decide how a certain reward fund (coming from rewards minted by the blockchain at a predetermined rate / inflation) is distributed. Given a wide distribution, and wide participation (yes this is a bit problem right now), and developing goods/services/other value exchange, we can bootstrap an alternative economy that is not controlled by any government or individual entity (although to some degree a small number have significant influence over the direction of the blockchain itself, but that is limited in scope).

For example, I frequently am using steem to tap into things like SteemMonsters purchases, VPS (privex), or accepting Steem for certain programming tasks. It really can be anything as long as you have two willing parties .

Permanence

I'm just going to point out that the examples cited are also reasons why it doesn't matter. People change, so dated documents should be interpreted with that in mind. But okay, there's probably so much that doesn't get dug up because they were deleted, and that's fair (although anything that has been public at a given time has a tendency to be archived somewhere anyway). Nothing much to say here, but to interact with the knowledge that it will likely stick around forever. You can edit posts out to make it harder to see immediately but anyone that wants to dig it up (edit history) will be able to do so.

One can also interpret this as saying that permanence encourages better behavior. Not that it stops people from staying pseudoanonymous if they so choose, so there's always that option.