None of the reasons given seem correct to me. Many of the reasons I see given are conventions arising from use and misuse.
The simple answer is this:
An IP address identifies a host, whilst a MAC address identifies an interface.
That is all.
Absolutely everything else, such as route aggregation, routing policy, and the behavioural differences between layers, stems from this primary distinction between logical and physical.
(Note: it remains a common - indeed, conventional - configuration & design error to bind an IP address to an interface. There is no such requirement and this complicates many networks. I was irritated to learn that IPv6 makes use of the MAC address in self-autoconfiguration)
(ObAuthority: I used to make ISP management systems for a living)
> An IP address identifies a host, whilst a MAC address identifies an interface.
... while a MAC can host multiple IP addresses (see vmware bridged network for guest OS), and the same interface can have multiple MAC addresses. And a devince can have multiple real/virtual interfaces.
The simple answer is this:
An IP address identifies a host, whilst a MAC address identifies an interface.
That is all.
Absolutely everything else, such as route aggregation, routing policy, and the behavioural differences between layers, stems from this primary distinction between logical and physical.
(Note: it remains a common - indeed, conventional - configuration & design error to bind an IP address to an interface. There is no such requirement and this complicates many networks. I was irritated to learn that IPv6 makes use of the MAC address in self-autoconfiguration)
(ObAuthority: I used to make ISP management systems for a living)