Equality constraints can involve primitive types, due to 18.5.3. It is incorrect to reduce a constraint like "<alpha=int>" to the *bound* "alpha=int", even though 18.2.4 says this is what should be done. (There's also a problem in the fact that 18.1.2 claims that primitive types are outside the domain of equality constraints.)

Primitives are already handled correctly by compatibility/subtyping constraints, per 18.2.2.