Yes! There is some absolutely terrible saddles out there, and some great ones. It's all about what fits you and your horse
Yes! my thorowgood Saddle put me in a awful position
But my tekna honestly get me in the position I have ever had!
Yes I do think it can cause bad position.!
I agree with everyone else, but it also may be the way the saddle was broken in. There's a woman at my barn who lets our trainer use her horse for the schooling program but we need to use her saddle and she rides much differently than the way our trainer teaches us. This causes discomfort and a struggle with position.
What Mark and David said! The saddle absolutely makes all the difference in your position. No-name, low quality saddles are just not made well, but even expensive saddles can be the wrong fit for you and cause your balance to be off. Also, if the saddle doesn't fit your horse correctly, it can cause you to have position issues. If you are constantly struggling to get your leg in the correct position, or if you have trouble holding your jump position, it is most likely your saddle.
I'm totally agree, with David and Mark.
I know a saddle can put you in a bad position. I have a really nice custom saddle that I rode a lot but always disliked. It makes me lean forward badly. I finally purchased a different saddle because I could and didn't want to be stuck fighting the saddle forever. Major difference!
Of course a saddle can cause bad position. Some saddle are just not made correctly putting you in a chair seat. If the saddle doesn't you, then you're constantly battling to stay in the correct position. Other saddles are so poorly made, that the saddle itself is off-balanced, affecting your balance and position.