There is always a grey area where a social media platform could be considered a personal and business purpose, however, typically they are usually trying to fill a specific niche and just happen to have a secondary purpose. Take Instagram for example. It's basically the social media platform inspired by selfies and self conscious teenagers yet there is an entire world of business related utility within in. Many people use their accounts to promote brands and products due to their high followers. You typically see a lot of that with fire arms, clothing, and gym gear. Facebook is another example of a dual purpose social media platform since it's primary niche is personal networking and yet there is a built in craigslist like feature now.
There are still many platforms geared to personal use only. These tend to be blogs which tend to have less followers and are more about expression. These have stayed consistent over the years as a place to write your thoughts without really caring if anyone reads them. I remember by first social media website platform was Xanga and I would write about anything without caring if someone would "like" my post or even comment on it. Today, there is blogger and word press which are places where people can just write. These I feel are some of the main social media platforms geared toward personal use.
From a business perspective, there are several social media platforms that my company uses simply because it adheres to our needs. We use Webex which is similar to Zoom or Skype and is used for virtual meetings. We use this to share presentations and even just to connect remote employees to our in person meeting. We also use Microsoft teams which reminds me of my old gaming IRC. In a way it's customizable to an employee based on their "teams" and it also acts as a file sharing and instant messaging platform. I find it useful if I need to send someone an informal message quickly opposed to sending an email. Linkedin is another platform that is geared to business. It's one of the best ways to maintain professional networks due to the limited personal touches someone can do. It's also a given that if someone is using Linkedin, it's for some sort of employment opportunity and so everything is professional. I always have my Linkedin link on resumes and I utilize Linkedin for job searching and even interview preparation.
Social media is an ever changing environment. I think there can be those focussed on personal use and business use together but there is also opportunity to have completely isolated platforms for each.
