Blunt Trailing Edges

Hi All,

Many modern aerobatic aircraft have blunt trailing edges on the wing and
ailerons. Can someone tell me:

1. Why it this done - what are the benefits and side effects. There is a lot
of contradictory information on the web and I simply cannot get to the
bottom of it.

2. What is theory behind it (a technical explanation please - I am an aero
engineer and understand aerodynamics and stability and control etc).

3. Who was the first to do it.

I have looked in all kinds of text books on stability and control and none
of them address the issue. This type of trailing edge appears to be unique
to aerobatic aircraft.

Thanks,

Steve