Why do we need drying machines

Why do we need drying machines if the dryer ironer can iron laundry with a residual moisture content of 50%?

The flatwork ironer dries and iron only straight linen (sheets, tablecloths, duvet covers, etc.), it is not intended for drying and ironing terry-loop goods and texture linen. If you iron on the dryer ironer linen with a residual moisture content of 50%, then the productivity of the dryer ironer decreases (for the linen to dry, it must be passed twice or ironed at a lower speed).