Server Message Block, the modern dialect of which is known as Common Internet File System, operates as an application-layer network protocol mainly used for providing shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. ...The Server Message Block protocol can run on top of the Session (and lower) network layers in several ways: directly over TCP, port 445via the NetBIOS API, which in turn can run on several transports: on UDP ports 137, 138 & TCP ports 137, 139 – see NetBIOS over TCP/IPon several legacy protocols such as NBF (incorrectly referred to as NetBEUI). Quote: WikiPedia article on Server Message Block
On Windows, SMB can run directly over TCP/IP without the need for NetBIOS over TCP/IP. This will use, as you point out, port 445.
Generally speaking, on other systems, you'll find services and applications using port 139. This, basically speaking, means that SMB is running with NetBIOS over TCP/IP, where, stack-wise, SMB is on top of NetBIOS if you are to imagine it with the OSI model.
Here's a visualization from Richard Sharpe, from samba.org.
Here's a slightly tweaked version to illustrate how you can imagine this on a Windows-based system.
The only "benefit" -- it's not really a benefit, as much as a requirement -- is that with SMB over NBT (NetBIOS over TCP/IP), you'll actually be able to communicate with a greater deal of implementations of SMB.
SMB does rely on NetBIOS for communication with devices that do not support direct hosting of SMB over TCP/IP.
NetBIOS is completely independent from SMB. It is an API that SMB, and other technologies can use, so NetBIOS has no dependency to SMB.
... It provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network. As strictly an API, NetBIOS is not a networking protocol. ...... In modern networks, NetBIOS normally runs over TCP/IP via the NetBIOS over TCP/IP (NBT) protocol. This results in each computer in the network having both an IP address and a NetBIOS name corresponding to a (possibly different) host name. ...Quote: WikiPedia article on NetBIOS
As you can see, the relationship would be Application -> SMB -> NetBIOS -> (TCP/IP, others).