A one armed, blind, tap dancer could achieve a good finish providing they had enough time.
But that's the whole point of hiring a pro'. Because they do it quicker.
Duh.
Without being pedantic (alright, being pedantic then) - I can see how being one armed, and blind may hinder your plastering.
But what is it about tap dancers that would be a problem??
All that jigging around would make the plaster fall off the trowel.