The saying goes if you’re not the customer, you’re the product. Now, you’re both. Every big social media app is testing subscriptions. It's a business model that comes with a perverse incentive. Just like airlines, if you make life worse, more people will pay.
I think the author might be referring to businesses who use social media to reach and connect with customers, however if your customers don’t see a value in paying for social media they won’t use it and it won’t be that necessary for those small and medium businesses.