It’s not always grammatically feasible or elegant to do so. Also, the singular “you” is much more common than the singular “they,” so your readers are more likely to expect it and are prepared for the potential ambiguity.
I often use “one” if I can get away with it grammatically and if it’s not unbearably pompous. (As a result, I often (in my own judgment) end up sounding bearably pompous.)
How is “they” any more ambiguous than “you”? Both can easily qualified with “all”.
It’s not always grammatically feasible or elegant to do so. Also, the singular “you” is much more common than the singular “they,” so your readers are more likely to expect it and are prepared for the potential ambiguity.
I often use “one” if I can get away with it grammatically and if it’s not unbearably pompous. (As a result, I often (in my own judgment) end up sounding bearably pompous.)