Am all for "going natural" as the next gal, but using soap, homemade or otherwise for routine laundry is O-W-U-T, out.
There is a reason why soaps were replaced by detergents, and those reasons are still vaild. Soap does not clean all types of stains, in all temps of water the way detergents can. More importantly soap never,ever totally rinses clean from fabrics. This leads in time to dull, grey and often laundry with a whiff about it.
That being said, will use soaps like Fels Naptha for grease,oil and other stains the respond well to solvent cleaners (naptha). Will even mix a bit of soap with detergent for foam control and or to give laundry a fresh "soap" scent, but that is the extent of it.
Besides, plain soaps on their own are poor choices for laundry day, this is why Fels and the copycat naptha soaps were so popular for laundry day. The addition of petrol made for a soap that cleaned well, without all the rubbing and scrubbing. Fels also contained water softeners, fabric brightening agents, and other chemicals that made it almost like a detergent.
L.