You have read this joke before.
One man is driving and listens on the radio:
"A drunk man is on the highway driving on the opposite way!"
And the man says, "One? there are a lot of them!"
Well, you do not want to be the drunk man.
I have never seen the need to calibrate my displays
This is probably because your displays are decently calibrated already.
My main two arguments in favor a minimal calibration (A. Color temperature on the monitor, and B. Gamma on the graphics card) are 1 "reproducibility" and 2 "starting point".
On a print design, depending on what system you are using, of course, you could end tweaking the file to match the print sample. In an ideal world, you do not need to tweak anything
But of course you must! Everybody does it!
No! the problem is that not everyone does it, not even people that should! If you have a problem with one provider you know the problem is on the provider side, not one "no man's land" problem.
If you have a good starting point to tweak methodically your file, then that provider needs X amount of extra saturation and Y amount of extra contrast.
This starting point is first of all to yourself.
If your camera or monitor one day wake up feeling sad, you will have a blue display on your monitor and you would correct it warming the file a bit... if the next day this monitor wakes up angry... dang, the warming you did the other day, plus the warm color of this day... you do not have consistency on your own workflow.
You do not want to be the drunk man.