As someone who grew up with Windows, I don't think these paths are that weird at all. Drive letter working directories just make sense, for example. The weirdest part is the (edit: HFS) compatibility mode (file.ext:substream).
One fun surprise is that because of codepage reasons, the Windows will use ¥ as a path separator in Japanese. In Korean, it's ₩. These characters represent U+005C, which is \ in Latin-compatible character sets.
I tend to use /dev/sda1 more than /dev/disk/by-path/pci-0000:00:17.0-ata-1.0-part1. Disk names are nice, but also often longer than 8 characters and usually not very unique.
Starting from A and iterating on through Z makes sense, for an OS that's designed for two drives at most. /dev/sda and /dev/sdb are no less arbitrary than A: and B:.
One major difference was that Unix was used on big servers and couldn't fit itself onto a single disk, so /usr had to be created. DOS and Windows never needed a second drive to boot, so they didn't need to embed their resources into the drive hierarchy.
Of course, you can mount NTFS volumes at any directory you wish since at least somewhere in the early 2000s. Very few people do it, but you can!
First floppy drive was A, Second B, and when internal Hard Drives came along they defaulted to C to be compatible with computers that had at least 2 disk drives.
If I rembember correctly, you could use the B drive even if you have just one unit. It was useful to copy files from one disk to another, even if you didn't had an hard drive as temporary storage
> The weirdest part is the HPFS compatibility mode (file.ext:substream).
HPFS had extended attributes, but not substreams. You are thinking about HFS; substreams were added to NTFS to support storing resource forks on network shares used by Macs.
Windows is younger than Unix, and Unix filesystem evolved has "evolved less" due to getting it right the first time, removing backward compatibility issues.
NTFS implemented it to be compatible with Mac. They then started using it for storing the Mark of the Web and other special system properties, but practical came much later.
One fun surprise is that because of codepage reasons, the Windows will use ¥ as a path separator in Japanese. In Korean, it's ₩. These characters represent U+005C, which is \ in Latin-compatible character sets.