According to the Linux Kernel documentation,[1] IP-aliases are an obsolete way to manage multiple IP-addresses/masks per interface.
IP aliasing can be used to provide multiple network addresses on a single physical interface.
Or indeed the opposite you could decide to replace the three different hardware devices with a single server to reduce the administration overhead.
In this case you can have three different addresses which are all on the same computer without having to install many physical network interfaces.
Another reason to use IP aliasing could be to have the computer on two different logical network subnets whilst using a single physical interface.