That's not exactly correct. The computer will adjust yes, but you can/may definitely notice the engine pinging, especially under load. My engine did it since the day I picked it up new, it doesn't have a "problem", it doesn't need a tune, it's just the way these hemi's are.
Even Ram says in the manual (paraphrasing): "some amount of pinging is normal". And yes it pings far less on 89/91.
So while it's fine to tell people to run 87 if they want, factually it's incorrect to say they won't notice. Many of us do notice the sound. Keeping in mind what pinging actually is, and that's it not exactly good for your motor, you may want to run 89 anyway even if you don't notice it as "not noticing" doesn't mean it's not happening. One possibility is that you might just be deaf