Acoustic treatment is a must for all kind of studio be it home or a big studio, without acoustic treatment the response of the recording room will interfere all the time with input and output signals.
Well planned and executed acoustic treatment can bring out the white noise inside the studio to super low, if very less sound is able to come in and go out it means the acoustic treatment of the studio is pretty rad.
Without the acoustic treatment lots of sine waves generated around you due to the oscillating parts of motor or any other form of mechanical device will result in bad acoustics and ultimately bad recording and producing scenarios, which will totally reflect in your mixing and production sessions.
In order to mix and master sounds perfectly the acoustic treatment of the room is must, the flat response of the studio monitors will not add much of a clarity to the song, if there is a certain amount of room reverb coupled with background noise.
If the acoustic treatment of the room is not done in the right way, then even the best mic, even the best amp or any kinda of rig as a matter of fact will totally fail to deliver the best quality sound and it is not a hardware fault it is totally dependent of the mistreated room acoustics.
The acoustic treatment should be rendered via understanding the acoustic geometry of the room and then adding absorbent and diffusers at certain points in the room where it is necessary, the sound and tonal profile of the room has to be as close to flat or lets say, should have very less reverb and internal reflection because that is something that we dont want to add during recording, because during recording multiple mics together we can face lot of issues that includes bad recording, lot of unwanted reverb, phase alignment issue and many other acoustic issues which are rendered due to bad room acoustics.