One of the reasons why moulded plastic chairs are widely used is that they can be stacked on each other.
Often people require additional chairs only for a shorter duration of time, when they have visitors to their house.
Having too many chairs can make the house or room look cluttered.
The plastic moulded chairs are convenient because they are designed so that they can be easily stacked on each other whenever required
It is also easy to remove one or more chair from the stacked chairs