gas - Dryer calls for 1/8 NPT plug - why not just direct

Any ideas why this dryer gas connection diagram calls for the "1/8" NPT Pipe Plug" - why isn't it just calling for a direct connection to the gas supply instead of having something t

EGT Probe Exhaust Gas Temperature Sensor - 1/8 Diameter

These gas connectors are corrugated and flexible, so they can be bent even in tight spaces. Heavy duty stainless steel. Easy and quick installment.

The Plumber's Choice 60 in. Yellow Coated Stainless Steel Flexible Gas Connector for Dryer Water Heater, 1/2 in. O.D. with 3/8 in. Fittings

EGT Probe Exhaust Gas Temperature Sensor - 1/8 Diameter

Irwin Hanson High Carbon Steel SAE Plug Tap 1/8 in. 1 pc - Ace Hardware

JMF Company 3/8 in. MPT Brass Hex Head Plug

DEWALT 3/8 in. NPT Desiccant Air Cleaner for Air Compressors DXCM019-0338 - The Home Depot

ANDAIR FS20 Series 3/8 Single Fuel Line Selectors SKU: ANDR-VLV-SGL-FS20

100133 Loren Cook Direct Drive Replacement Motor - All Around Industry Supply

Why won't this 3/8 male connector for a natural gas dryer fit a 3/8 female connector? - Home Improvement Stack Exchange

Unique Bargains Pipe Fitting Reducer Adapter 1/8 NPT Male x 1/4

4 All Stainless Steel Oil Filled Pressure Gauge - 3/8 NPT Lower

3/8 NPT Female to 1/8 NPT Male Brass Pipe Adaptor/Adapter Straight Reducer/Reducing Coupling Male to Female

FITTING, ADAPTER, 3/8 NPT MALE, BRASS, FOR MECH. TEMP. GAUGE

Proline Series 1/8-in x 1/8-in Threaded Street Elbow Fitting in the Brass Fittings department at