You're not going to herniate a disc getting up to a 135lb deadlift. But a 135lb deadlift would probably make most people's chronic lower back pain go away.
I love DLs, but you need to learn to do them properly. You can herniate a disc brushing your teeth.
What DLs do as a side effect is teach people how to pick up things properly. Most people are too tight in the their ankles, hips, and rest of their posterior chain so they are picking things up incorrectly all day long. This sets them up for injury. Learning to DL properly is a great way to teach how to properly pick thing up, and I agree it will likely help with most people's back pain. But, doing anything improperly can cause injury.
recommending deadlifting to people with backpain sounds completely insane. At the minimum they should tell to do strength exercice under the strict supervision of a very good professional
