It is possible up to a point. A solo operator can handle a limited number of clients before the work becomes too much to manage well. Tools that automate reporting, keyword tracking, and audits help a lot. Some people also outsource writing or link building without building a full team. But there is a ceiling to how far you can go alone, and at some point growth really does require more hands on the work. What do you think is the realistic limit for what one person can handle in an SEO business?