Bluetooth Protocol (rfcomm, L2cap And Acl)

From what I've read from Bluetooth Essentials for Programmers, this books mentions some points that I dont quite understand. RFCOMM is a reliable stream-based protocol. L2CAP

Solution 1:

The encapsulation could be at the "device" driver level so it would be invisible to you, its like you never "created" an Ethernet packet, but you still able to use TCP/IP natively, how come? same thing here, RFCOMM uses L2CAP, but doesn't mean you need to know L2CAP to use.

Usually encapsulation is used when you don't want to hassle with something else, in this case they didn't want to hassle with the signalling issue, RFCOMM is used for Serial interface, so they didn't want to handle the signalling issue of Serial interfaces