There is some truth to this. The goal is for more front ends to develop on the Steem blockchain. This doesn't mean you shouldn't build a following here. Your following is not Steemit-specific. It will remain in place no matter how many new interfaces come along. Steemit is just one way to access the Steem blockchain. It could vanish tomorrow and your account, wallet, followers, posts, and everything else would remain intact, and accessible through sites like Busy.