No, it's just a limitation on the pricing calculator. You are charged for the compute resources that you will use so the calculator just tries to calculate how many session hosts (VMs) that you will need and how many hours per month they will be allocated for depending on your requirements.
If you want a dedicated personal desktop for each of your users then you will have 10 VMs (of whatever size/spec that you choose), 10 OS disks (1 each) and then you just need to decide how many hours per month each will be running for. If they are always on then it will be 730 per month on average.