Why does the command "spanning-tree mst simulate pvst disable" exist

[helenokeeffe]

That's all really. Why would you turn it off? What is the advantage. If you're not receiving PVST BPDUs, you don't need it, but why turn it off?

[jossabor]

http://www.cisco.com/web/techdoc/dc/reference/cli/nxos/commands/l2/spanning-tree_mst_simulate_pvst.html

[helenokeeffe]

When you use the spanning-tree mst simulate pvst disable command, specified MST interfaces that receive a Rapid PVST+ (SSTP) bridge protocol data unit (BPDU) move into the STP blocking state. Those interfaces remain in the inconsistent state until the port stops receiving Rapid PVST+ BPDUs, and then the port resumes the normal STP transition process.

OK, that's what it does, but why? the only effect it has is blocking your ports. 

[jossabor]

 To prevent specific MST interfaces from automatically interoperating with a connecting device running Rapid PVST+,