Just letting bottles soak in hot soapy water

I just thought of something. Is it really necessary to scrub every single bottle part, or can you just let it soak in hot soapy water and rinse and then sanitize? I feel the soapy water would efficiently get through the nooks and crannies. I rinse them after use so there's no hard milk residue. It would also save a ton of time if I didn't have to scrub every single piece. I mean, don't restaurants just let dishes sit in hot soapy water then rinse?