Why not use a vise? A vise is a latter invention of flytying - yet those fly dressers of old were able to tie fantastic dressings with just thread, scissors, and their fingers. In the past, I did use a vise and tied quite well. But I was challenged by the works of a few present-day tyers who did not use the aid of a vise. These tyers not only tied amazing patterns by gripping the hook with their fingers, but they also fished these works of art! Enter: Inspiration...and morph it into a personal challenge. Why not at least attempt tying in hand? (And then fish it before anyone can laugh at my attempts.)
Suffice it to say, my first attempts came out decent. I showed it to my mentors who tied in hand and they were quick to encourage my efforts. That's all it took for me to dive in headlong. To be honest, it's surely not that simple.
A novice tyer in hand will struggle with managing materials until they develop the muscle coordination in their digits. Like any undertaking worth attempting, repetition goes a long way to decrease the level of difficulty. Once the skill becomes comfortable to the in-hand tyer, the challenge continues in building patterns that require a mastery of managing difficult materials to wrap on a hook. As one studies the history and patterns of these vintage flies, there are enough discrepancies to make a terrific puzzle. Even the authorities of the late 1800s and early 1900s that wrote detailed books on Atlantic Salmon Flies had conflicting ideas of their "mastery". It is no different of tyers to this day. Each have their own personal reasons to attempt such flies.
One thing that impressed me is how ghillies of Scotland and Ireland at the turn of 20th century would tie flies for their angling clients on famous rivers. These fishing guides would tie up flies in hand on the riverbank, or perhaps in the ghillie hut near the river and handed these "fresh" patterns to the client to fish for the salmon. As beautiful as their flies were, they were still hooks presented to fish in the hopes of fooling a salmon.