IPv4 adresses fit in a standard 4byte integer, that might be a reason.
Quite frankly, if they didn't allocate full /24 to single entities (including localhost...), we might still have enough addresses left.
Quite frankly, if they didn't allocate full /24 to single entities (including localhost...), we might still have enough addresses left.
Even if we hadn't wasted /8s on huge allocations to single companies, and things like 240.0.0.0/4, we'd still be basically where we are today, with v4 address space being scarce and traded as a commodity.
For how long?
IPv4 is just inefficiently allocated in general. Why does the world need 10.0.0.0/8 in addition to 192.168.0.0/16? Isn't 65k addresses enough? Is there a private organization in need of 16 million addresses?
Not to mention AMPRNet (amateur radio) owned the entire 44.0.0.0/8 up until 2019 (a portion was sold off to Amazon). That may have seemed reasonable in 1980 but now it's just plain crazy.
Plenty of mobile phone networks have well over 16 million subscribers, and they typically don't have enough public IPv4 addresses for everyone. This has led to really hacky stuff, like using DOD IP ranges as psuedo-private space, or re-using private IP addresses in different regions (which can't be fun to maintain.)
Some networks have fixed the problem by using NAT64 - forgoing IPv4 altogether internally, and translating to public v4 at the edge. (Works surprisingly well, T-Mobile US has been doing it for the better part of a decade.)
This is why 192.168.0.0/16 is often used for services like libvirtd, kubernetes and docker. And the use of the range by those services makes it even more unwieldy to try and put some other LAN in there.
You can work around these considerations if you want, but many people won't. When you're the network engineer responsible for designing a company's networks, you'll be wanting to keep things simple and robust. When you're called in at 3am on a Sunday because the network is down, you better hope your ability to recover doesn't require making a bunch of subnet calculations because you decided to try and use the pool of available IP addresses efficiently.