Like any other fruit tree, pears can benefit from pruning. And there is nothing inherent to pears that makes them any more sensitive to this practice. Ideally pruning should be done annually, beginning in the tree's first year, so that you are never pruning out too much at any single time. This link may help but in my experience, the best way to learn how to correctly prune fruit trees is to watch an experienced fruit grower/orchardist do it. They are not pruned the same way ornamental trees and shrubs are pruned. Many nurseries that sell fruit trees will offer free pruning classes in late winter....check them out.

If you live in an area that experiences a lot of fire blight, that might be the reason the seller told you to avoid pruning. The pruning wounds present on mature trees can be large enough so that the pathogen will enter the wound and than can be devastating. This is why you start pruning while the tree is still quite young, so that the requirement for pruning as the tree matures is reduced to just some annual tidying up and does not become a major project. But if fire blight is not a big concern in your area, then there is no valid reason NOT to prune :-))

Pears NEED to be pruned same as any other fruit tree. I think pears need even more pruning than an apple. Follow your instincts and hack away. You'll have to do the same thing 2 or 3 times per season. It takes a lot of work to keep tree shape where you want it. But it can & should be done.

Thank you both for your replies! I will definitely give it a good (judicious) pruning start later this winter and feel much more confident about the result!

Pear trees are my least favorite fruit tree to prune. They just want to grow straight up! Beware that they will throw out more growth wherever they are pruned. I've decided that this season I will lop off the leaders because they are starting to get too tall and that is all I will do other than obvious broken or crossing branches.