Yes it can! There is no such thing as a reed that is too easy but there is point at which the reed is so easy it becomes difficult, if not impossible, to maintain good constant air pressure. Any change in air pressure will cause the pitch to fluctuate.
Reeds that are harder to blow are not as susceptible to small changes in air pressure. If the reed is a hard reed, you must blow hard to make the blades vibrate, so subtle shifts in pressure won’t affect the pitch much, if at all. In contrast, a very easy reed will react to just a sigh (ok maybe a little exaggerated, but it makes the point.)
An easy reed will be affected by very small changes in pressure. So very easy reeds can be used, but to maintain a steady pitch you will either need excellent control over your blowing, or a PitchGuard fitted to control the air pressure to the chanter reed.
