Not quite. The kernel documentation notes that IP aliasing was the original way to have multiple IPs per interface, but is now obsolete, as multiple IPs are directly supported now (and by "now" I mean 2009-ish, with the introduction of iproute2): https://docs.kernel.org/networking/alias.html

In addition, the manpage for ip-address makes this clear:

> The address is a protocol (IP or IPv6) address attached to a network device. Each device must have at least one address to use the corresponding protocol. It is possible to have several different addresses attached to one device. These addresses are not discriminated, so that the term alias is not quite appropriate for them and we do not use it in this document.

https://linux.die.net/man/8/ip

Since when is it there? Because i had interfaces with both v4 link-local and DHCPv4 addresses since i can remember.

IPv4 itself doesn't say anything about how many addresses you could have on an interface, not that I recall.