What is the reason that cleaning nebs with vinegar/water is no longer recommended? (pls correct me if wrong) references/links? What is best (not boil)

Not strong enough. Vinegar is not strong enough to kill the bacteria that are now found in many nebulizers. Recommended methods include boiling or microwaving for 5 minutes, soaking in a solution of 1 part bleach and 50 parts water for 3 minutes, soaking in rubbing alcohol for 5 minutes, and soaking in 3% hydrogen peroxide for 30 minutes. Always follow the nebulizer maker's recommendations, however.
DISTILLED WATER. And if safe, a teaspoon of bleach will do.