only sorta kinda true.  For pretty much every app and front end built on top of the steem blockchain to run, they depend on the api nodes that Steemit, Inc. runs at the cost of several million $ a year.  If Steemit, Inc. stopped subsidizing the rest of the players on the blockchain by paying the costs of running the servers for the api nodes, nothing would work.  It is possible that things would eventually start back up if someone else decided to foot that cost, but currently it doesn't look like any of the apps or front ends could bear that cost.   So pretty much, if Stinc goes under, the blockchain for all intents and purposes stops even if witnesses are still running.