Treating You Like You're Incompetent, Incapable, And Unimportant

Why would someone who cared about another person treat them poorly, like they're incapable, unintelligent, untalented, unimportant, or unable to learn something or accomplish something?

Simple answer: They wouldn't.

A person who cares about another person, whether they are the person's parent, spouse, fiance, sibling, friend, teacher, doctor, therapist, neighbor, coworker, or anyone else would NOT treat them with such disrespect, dishonor, and disdain.

If a person cares about another person, they treat that person with courtesy and respect. They would be supportive of them in their endeavors and goals, not dismissive or belittling.

Any ACTION that they would do toward or regarding the person would be positive, not negative.

Supportive- not oppressive.
Encouraging- not demeaning or invalidating.
Helpful- not sabotaging, ignoring, or blocking. 

When a person is condescending, disdainful, manipulative, or unsupportive toward a person whom they claim to be a friend to, or care about, they are being dishonest.
Their actions show their true intentions and motives.

Why would a person claim to "care" if they really don't, if their real intention is to cause some sort of problems for the person?
Simply so they can get close enough to the person to be able to cause the problems, or to gain control over them, or to get something they want from them.

They also likely do not want their true motives to be exposed, so they keep saying they care about the person, convincing the person and everyone else around that they really DO, that they mean no harm, that they are a "good person", that they are there to support the person, and that they have no ill will or intent toward the person.

If everyone believes that they really do "care" about the person, then whatever they REALLY do is more likely to go unnoticed; people would not expect anything negative coming from them.