Line fluctuations can cause misreads and miswrites.

His [John, King of England's] Acts and Orders for the Weale-publike were beyond moſt: he being either the firſt, or the chiefeſt, who appointed thoſe noble Formes of Ciuill gouernement in London, and moſt Citties, & Incorporate Townes of England, endowing them alſo with their greateſt Franchiſes; […]

juxtamedullary nephron

If they had allowed single-character accelerators, Windows wouldn't be able to determine whether the character was input or a shortcut.