[adrian_b]

Even if you do not want the new OS to run on anything else but your own laptop, that still needs a huge amount of drivers, for PCIe, USB, Ethernet, WiFi, Bluetooth, TCP/IP, NVME, keyboard / mouse / trackpad, sound, GPU, sensors, power management, ACPI and so on.

The volume of work for rewriting all these is many times larger than writing from scratch all the core of a new OS.

Rewriting them requires studying a huge amount of documentation and making experiments for the cases that are not clear. Most of this work is unlikely to present much interest for someone who wants to create an original OS, so avoiding most of it is the more likely way leading to a usable OS.

[spicybright]

I think you're still missing the point here.

Not every hobby OS needs or even wants networking, gpu support, even storage I/O, etc. See TempleOS.

The goal typically isn't to make a fully featured OS.

[adrian_b]

If you do not want those features, that means that the OS is not intended to be used on a personal computer, but only on an embedded computer.

For dedicated embedded computers, the purpose for an OS becomes completely different and compatibility with anything does not matter any more.

Not only personal computers cannot be used without a huge amount of device drivers, but even for a very simple server, e.g. an Internet gateway/router/firewall or a NAS server, the amount of work for writing the device drivers, the file systems and the networking part would be much more work than writing the core of a new OS.

Only for embedded computers the work needed for device drivers can be smaller than for the base operating system.