If you have a nice system why do you really need room treatments?

Cause it corrects the way the room is interacting negatively with your system.  I like the look of my treatments and they are functional.  As @jpan states, you won’t know till you measure and fix things.

Here’s a video that speaks to this topic.  The clap example he gives at around the eight minute mark illustrates the point well.

https://youtu.be/DrPvXt5Anz4?si=Ka4Qs2-78ROMYVaY

This entire thread is a mess. OP doesn’t have treatment but does have it.  Why are people dependent on Dirac, by the way I use it too.  It’s all over the place.

I hardly feel that corner bass traps and very modest absorption panels in a furnished room is a serious effort to acoustically treat the room.

It may not be but it’s still treatment as well as your rug.  You treat the issues you have in the room and not every room requires the same level of treatment.  A lot of your responses as well as the thread title make it sound like you think if the system is good then it shouldn’t need treatment in any room, only to find out you have treated your room to manage issues you have.  You can over treat/dampen a room for sure but I’m not sure most folks on this site are doing that.  They are doing just enough to sort out issues.  I guess it’s just between your thread title and opening comment that you make no mention of any treatment then it turns out you have some and have done some measuring (I think both of those things are good to do).  That’s what made it seem like you’re all over the place.  

Oh, and you both hate bookshelves but wish you had them.  I’m not judging you just making some observations that make the point of the thread hard to follow.  By they way, how do you like your 901s?

Disagree.  If the reason is the pursuit of the best sound the system can create in that space then it has nothing to do with being conditioned to think acoustic treatment equals true audiophile.  What is the definition of sounds fine by the way?  There are plenty of videos online you can watch and hear the massive difference in the before and after.  I don’t want to treat my room using furniture, I want to use acoustic treatment designed specifically to manage issues I have in my room.  I have no idea what piece of furniture I need to add in order to manage a +3db rise at 50hz.  However, I can do some research and find acoustic treatment that can help flatten that out.