Many can do the same, but they have 1 year of catching up to do (or would not use BTC as a platform). Nor do I doubt that anyone would be as generous as the XCP founders, to self-fund their development. Also, first mover advantage and all that. Also if someone has the idea, skill and motivation to do so, they will likely just apply to be hired by XCP. (So they can work on an existing, and repeatedly audited platform). I don't see a logical motivator to push forward on another BTC-based platform. If the motivation is profit, proof-of-burn remains superior. If the motivation is technological, they can work on existing open-source XCP software.

You have to realize that companies like Overstock issue NDA's (non-disclosure agreements) that people have to sign. They can't say anything, it's in their contract. It's up to Overstock to make the announcement, not Counterparty devs.