The advantage of Steem is that generally speaking, the blockchain and platforms associated with it are much more mature in many ways. For instance, there are already many interfaces to the Steem blockchain. Not so with the clones. Also, it is already a distributed system, not so with at least some of the clones and we can see the consequences with Weku right now.

To make an old school comparison, I think Steem has the opportunity to become the Usenet of the 21st century. While Usenet still exists, it is hardly used anymore (relatively speaking). The great thing about it was that it was essentially a distributed forum by which people could communicate about every subject imaginable. Web forums ultimately replaced it. Features were much improved but the communities were fractured. With Usenet there was no need for cross-platform blogging. Steem COULD become the backbone of all (or at least most) social networking/blogging. It won't be a matter of chosing a platform anymore, just choose your preferred interface. There are already options to interface Wordpress with Steem, why not other blogging and social networking platforms as well?

There is room for more than one of course but I think for the clones to succeed on the level of Steem they or going to have to do more to differentiate themselves or Steem is going to have to really drop the ball (which is entirely possible).