Why Consumer Drones don't use multi-blade (more than 2) propellers?
There are a number of related questions on the site for more information about this. I'll link them below.

The short answer is that two blades will be the most efficient use of energy. If the drone needs a better climb rate then adding extra blades is an option, since you can't make them any longer. The downside is that it will reduce efficiency and thus your battery time. 

I can't find the question at the moment, but Peter Kämpf mentioned in an answer that theoretically one blade would actually be most efficient except that you would have to provide counterweight to balance it. The counterweight with no excess thrust would negate the advantage, but that's just an illustration of how the fewer blades the more efficiency. 

Here are the links for more reading:

What's the difference between a two-blade prop and three-blade?

Is a propeller with two long blades more efficient than one with three shorter blades?

How does blade solidity ratio relate to thrust/power/torque of a propeller?

Why are three-bladed helicopters relatively rare?