Considering that it's pop-psychology article, I certainly wouldn't take it as gospel. In fact, the article's title stinks of scaremongering.
For starters, does this article clearly differentiate between being alone vs. being lonely? Solitude isn't synonymous with loneliness. Someone can still engage in regular human interactions, have various types of relationships (e.g. platonic, familial, professional, romantic, sexual, ect.), and easy access to various social benefits, but deep down, be just as miserable and unhealthy or even worse than in solitude. There are individuals who are highly introverted, loners, asocial, and/or have little to no social orientation towards humans, and are very much healthy. Some even thrive the best alone, and gain various benefits from solitude (e.g. more peace and calmness, less stress, little to no distractions, greater creativity and imagination, more energy, more freedom, more independence, greater self-knowledge, ect.). For romantic and sexual relationships, there are many who aren't interested in them and are in good to excellent health. Cases in point, asexuals and aromantics. In short, human interactions and relationships aren't the health panacea for everyone.
Keep in mind that these studies focus on average neurotypicals. So far, I haven't found any non-biased, peer-reviewed scientific articles on individuals who thrive in solitude and/or aren't socially oriented to humans. One of the challenges could be locating enough asocial humans for a good sample size. Perhaps there isn't enough funding or motivation to conduct these observations. Nevertheless, the dearth of research in asociality and alternative social orientations leaves a significant gap in fully comprehending human psychology and even health.
Bottom line, everyone has different psychological and social needs. Not everyone experiences negative health consequences from lack of human contact or relationships.
