But then the question was posed about canard wings on aircraft, which are
basically rudders on front. They don't destabilize the airflow.


Destabilizing the airflow isn't the issue. Destabilizing the aircraft is!

A pilot can't control a plane with a canard. You need fly-by-wire (i.e. a
computer to control the canard). Humans can't react fast enough. The Wright
brothers had a forward horizontal stabilizer on their first aircraft and it
quickly disappeared from aircraft design until small, fast computers came

Not true! Canards are not rudders they are wings providing lift. They prodive
stability holding the nose up. They are set to loose lift at an angle slightly
less then the main wing. That way when the nose comes up lift is lost and the
nose comes back down. This helps keep the plane more stable not less. Also
the plane is less likely to stall. No computers in those little one and two
seaters from Rutan.

http://www.rutanaircraft.com/