i am sure you have the right intentions but programmers tend to need some time to get up to speed. besides, nobody really wants to work at a shop like that. every employee will think you don't care. meaning you will have to deal with people leaving you for a more dependable company. recruiters won't like you as they are unlikely to get their money and need to find new people all the time.

it is possible if you offer employees a lot of money. some financial companies do things like this (fire 5% every year) and manage quite well but i doubt it works in sectors where personnel costs are significant.

If you have been fired in a week or so then you know the psychological impact of these practices.