The second reason is due to the notion of electronegativity. An electronegativity theory argues that fluoride should be largely ionic. Acidity is one of the best described measures of ionic content and it clashes with electronegativity. What to do? Dispute acidity?

I am working on writing a book that I intend to title, “The Nature of the Chemical Bond, Revisited”. In that book I discuss the ionic theory of attraction, Pauling’s proof of it, his theoretical bases for electronegativity theory, his empirical calculation of it, argue weaker than expected bonds disprove the theory, and provide a model which is consistent with a model largely relying upon an inverse square law consistent with the physics of electromagnetic forces. I am working on explaining the different bond strengths that led to electronegativity theory and to explain why some bonds should be stronger than expected and others (the metal hydrides) weaker. Because the laws of physics demand an inverse square relationship, I explain acidity consistent with those forces. I think you should find that electronegativity is false and acidity is not controversial at all. I would hope that you would also learn a whole lot more about chemistry than electronegativity. I have written about bond types, strength, length, reactions, mechanisms, orbitals, atomic theory, Bohr atom, etc.