Decades ago A-frame tents were the standard design. They had a zippered door or tunnel at one or both ends, without a vestibule. The fly was built like today’s shaped tarps, with a beak or awning over the front door.
Somehow those ancient (cough) backpackers survived one thousand and one nights or more in all kinds of weather, without vestibules. After shimmying in through the door, we maneuvered around piles of gear, a running Svea gasoline stove, and the occasional dog all inside the tent in inclement conditions. Then other designs swept through the industry.
Vintage A-frame tents, mostly without vestibules, discussed here with many photos:
https://backpackinglight.com/forums/topic/storm-proofing-the-side-panel-on-a-lightweight-a-frame-design
— Rex


