Blown in insulation is cost effective but has its limits.
Blown in insulation, both fiberglass and cellulose is an affordable option. This means lower upfront costs when building. Installed in both loose fill and dense pack form, can do a good job insulating your home if installed correctly. It is also easier to to remove and replace when doing remodels and renovations down the road vs spray foam.
Blown in insulations biggest disadvantage is air leakage. Although it is better than batt insulation, blown in fiberglass and cellulose suffer from high air leakage causing heating and cooling loses. The air leakage can also cause condensation issues, leading to moisture and mold problem. This air leakage means poor performance and significantly lower R values and BTU retention vs what a manufactures state based on controlled lab tests.