Usually the huge sites or heavy traffic sites need a VPS for allocated resources such as CPU, RAM, Disk I/O, etc. But having a VPS means that you have to pay extra for the cPanel license along with the management of your VPS server. That makes the cost too high for a single site or a couple of sites that you may have. Our semi-dedicated plans are in fact shared hosting with VERY high dedicated resources that you can rarely find in simple shared hosting plans. And they also include the cpanel, the management, the multiple backups, domain, and much more!
Simply we don't have high expenses, we are a small team and we are willing to keep it as is for lifetime.