Why are we requiered to have less than 5% timeout to HOST a tournament?

It is just one of the requirements that was determined. I would think it is best if tournament directors would not abandon games and timeout in games so that they understand the professionalism and sportsmanship that should be exhibited during tournaments.

i prefer if it was 10% timeout

Most tournaments do use a 10% timeout ratio. It is all up to the tournament directors discretion.