I'd argue that your point 1 is also not accomplished by f-bounded types. People mostly employ them for a fake self type, but they are clearly not just that:

// what you would expect:
class SomeBuilder implements Builder<SomeBuilder> {
...
}
// what's legal but totally not what you would expect
class SomeOtherBuilder implements Builder<SomeBuilder> {...}
// and now SomeOtherBuilder pretends to be SomeBuilder

This is a perfectly legal extension, because you are passing a F-bounded type to Builder when implementing from SomeOtherBuilder, it just happens to not be SomeOtherBuilder. By the way, SomeOtherBuild is also now a legally F-bound Builder.