The role of the gluten in an acid environment
The link you are looking for is the balance between structure provided by gluten and structure provided by starch.  When there is a lower percentage of gluten, starch has to remain intact to give the bread structure. So, when using a lower gluten flour to make bread you use more sourdough starter so that you can develop a higher level of acidity. This acidity reduces activity of the enzyme alpha amylase and leaves more of the starch intact.  Not developing significant acidity quickly enough will lead to a gummy dough that will collapse during baking.