Is salt important to the texture of dough? Does salt have any effect on the texture of doughs?

My mother in law has gone on an ultra low salt kick and has taken to not putting salt in anything. This includes her pierogi dough (you know the potato &amp; often cheese filled dumplings common to eastern European peasant cooking).

I've noticed that her pierogi dough seems tougher (like she's re-rolled the dough, which over works the dough and as I under stand makes more gluten) without the salt that used to be with it. It's a rather simple dough: flour, water, vegetable oil and salt. I imagine I'd get the same effect with a pie crust as well.

Is the salt inhibiting the gluten formation or doing something else or am just imagining this effect?
Salt toughens gluten and makes the dough less sticky.  So with that said, it would make it much easier to work in too much flour and make the pierogi dough more dense.  Do a search on the following page for "biscuit" and read the few paragraphs before.  

http://www.saltinstitute.org/Articles-references/References-on-salt-use/References-on-salt-use/References-on-salt-in-food