The Windows support is bad because OCaml is a PL designed by people who are deep in Linux life. Windows is not something that keeps them up at night. (Which isn't to say they didn't try, just, you know, not as much as it takes)
One of the things people often neglect to mention in their love letters to the language (except for Anil Madhavapeddy) is that it actually feels UNIXy. It feels like home.
If that's what you use as your yardstick of what's Unixy, then I guess you don't consider "find" to be Unixy, in spite of being one of the early Programmer's Workbench tools.
Short options were a compromise to deal with the limits of the input hardware at the time. Double dashes were a workaround for the post-dash option car crash traditional Unix tooling allows because teletypes were so slow. There is nothing particularly Unixy about any of these options other than the leading hyphen convention.
Caml was developed in 01985, Linux was first released in 01991, and Caml was extended into OCaml in 01996. I don't think the developers were using Linux at the time; SunOS 4 would be my best guess. I didn't work on it, but I was in the sort of internetty environment that OCaml came from, and I was using Solaris at work and got my first Linux box at home. As another commenter mentioned, the command line follows Unix conventions rather than the Linux conventions from GNU.
It's just sort of anachronistic. Caml was no more designed by people deep in Linux life than James Clerk Maxwell was into aviation or Christopher Columbus liked to visit the Massachusetts Bay Colony. They probably would have been, but the timelines didn't allow it.
Sure. The larger point was about Windows. You would or would not agree that people doing PL research on SunOS workstations (or whatever UNIX) would also not give a shit about Windows?
Windows didn't exist in 01985. I mean, Microsoft did release a product by that name at the end of the year, but it wasn't an operating system.
I remember that in 01998 or 01999 I asked Andrew Tanenbaum, a different European CS professor, what he thought about Linux. His impression was still that it was some kind of hobbyist project for people who (paraphrasing here and reading between the lines) couldn't afford a real computer. So I suspect that, even when Caml became OCaml, its developers saw Linux as belonging to the same crowd as Microsoft Windows, rather than to the systems they were used to.
But even that Windows/Unix OS dichotomy didn't exist when the programming language was designed. They might have been thinking about Unix vs. VMS, or Unix vs. GCOS, or Unix vs. Oberon, or BSD vs. System V, but definitely not Linux vs. Windows.
One of the things people often neglect to mention in their love letters to the language (except for Anil Madhavapeddy) is that it actually feels UNIXy. It feels like home.