This is a weird bone to pick. It's similar to saying "obesity isn't a problem, overeating is."
Like, yeah, sure, you can frame it that way if you want. But what utility have you added? So that you can build up to the conclusion that lonely people ought to go socialize properly? That's pretty tautological advice there mate.
I read GP's comment more along the lines of "loneliness is akin to a hunger that drives the lonely person towards seeking deeper personal connection with others". Similarly to how some people argue that "boredom is a gift" which leads to creativity[0]. Instead of placating that hunger with poor substitutes, be it TV, netflix, social media, drugs etc, that drive can serve as motivation to seek out connection, the lack of which is ultimately the root cause of the loneliness.
[0]https://www.bbc.com/culture/article/20200522-how-boredom-can...
Loneliness definitely is a problem if a pandemic makes socializing in person effectively impossible. We need people to be able to overcome their loneliness, temporarily not in person, so they don't risk spreading a lethal virus around.
Regardless of the hype, social media is a poor substitute to physical human interaction and is more anti-social than it seems. I'm sorry, but Internet friends you've never met aren't your friends. They won't support you in the ways that really matter, they won't know you as you are rather than how you portray yourself. Internet communities have the capacity to broker relationships but those relationships have to flourish outside of those communities to endure.
Loneliness is good. It forces you to do the unpleasant, inconvenient and potentially risky act of actually getting to know someone and include them in your life. People need to allow themselves to feel it so they can act on it and truly relieve it instead of wallowing in digital emotion machines that simulate human interactions.