Their main selling point which is 'earn money on social media' is going to be the most boring thing when every website uses this tech.

With SMTs etc., isn't there supposed to also be a widget of sorts that any website can add to their page to reward users with steem (but they'll be able to name the currency whichever way they want)?

Granted, why go with steem when they can invent their own currency.

But, smaller websites won't have the money to invest in doing that, whereas the steem widget will be plug-and-play, so getting rewarded in steem with be the default way to do it on the internet, I guess, so steem will have the upper hand, initially at least.

Consider also that steem is already big-ish, whereas a new coin by another site will be initially small. Users, being human, will want to be rewarded with more, not less, money!

They will also want to cash out easily. Steem is already in many exchanges. There are sites like bitwala that issue prepaid visa cards that you can top up with steem and use like a regular visa card to purchase stuff in the real world. Will the new coins of X website be able to do that at the very outset?