Do you actually need a bed frame?

You do not strictly need one, but a frame solves real problems. It lifts the mattress off the cold floor, improves airflow to reduce moisture and mould, keeps dust and pests away, and makes the bed far easier to get in and out of. A frame also protects the mattress warranty, which often requires proper support. Putting a mattress straight on the floor works short term but invites damp and wear over time.