Random internet Quaker: *mentions BYM*
Me: "which one? BritYM or BaltYM?"
And that's only with the context that the person had mentioned "unprogrammed". Burundi YM, Bware YM…
Friends, there are WAY more than 26 YMs. (There's about 20 in Africa!) A single letter + "YM" is likely to be ambiguous.