https://bugs.winehq.org/show_bug.cgi?id=48584
--- Comment #7 from Zebediah Figura z.figura12@gmail.com --- (In reply to Scott from comment #6)
The piping is to simulate the command being entered from the program's directory location as entering the wineprefix command from any other location will fail.
That seems strange, if the "--workdir" command does indeed act as one would expect. If nothing else, "cd" should be enough to achieve what you want. I'm also not sure that "cmd" executed like that will ever terminate, which probably isn't desirable either.