Well, in my dialect of Engish, 'ken' and 'can' are nearly indistinguishable, and there are many "can's" in Unicode; probably more than "mark's".
I'm reminded of what farmer is supposed to have once said about his produce: "We eat what we can, and what we can't, we can." > P.S. On the other hand, if you asked him nicely, Mark might > find the more marked form, NFD, to his liking, especially > since it is likely to contain more combining marks. Mark > is definitely in favor of markedness. I, on the other hand, > am definitely in favor of kennings, but we have found little > practical or architectural use for them in the Unicode > character-sea.