To your point, if a telegraph operator handed me a message I didn't understand, I could just say, "Hey, I don't understand this message. Can you explain it to me?" because that is social skills.
That I can have someone translate to and from Urdu for me does not mean I have the social skill required to communicate via Urdu. Likewise, that your parents can ask you whether something is spam or not doesn't mean they have the social skill required to communicate via email.
Wikipedia defines social skills as:
"A social skill is any competence facilitating interaction and communication with others where social rules and relations are created, communicated, and changed in verbal and nonverbal ways."
If the ability to effectively communicate via a medium doesn't satisfy that definition, what does? You are welcome to use a different definition, but that's what I am referring to by social skills.
Whether using your definition or another, my point still stands that social media does not lead to GREATER social skills than previous generations possessed.
Not being skilled in ALL aspects of socialization isn't the same thing as lacking social skills in general.
I never claimed that social media leads to objectively greater social skills, there's no reason why being able to write a great email is inherently superior to being able to write a great telegraph message. However, one skill is undeniably more useful in this day and age. It does not matter if you call it a social skill or a technological skill, the fact remains that there are people who know how to communicate effectively via social media, and those who don't, and just because you are comfortable in the latter category does not mean your daughter will be too.