Dear Henry, you are right .... that's what I am saying.
And - no matter what I will say, I won't convince and I do not want so either.
The three principles of drive we encounter in analog phono playback are all three with merits and flaws.
None is perfect - none provides what physic asks for in stable speed.
As none can provide controlled stable speed without acceleration.
Unless we minimize the platter's mass - which we don't really want .... for obvious reasons.
It is about getting the platter to speed and preventing it from slowing down again.
The job of the drive is in the first only ... only ... to get the platter to the required speed.
Once that speed is obtained, it is about preventing the platter from slowing down.
It can't be about "controlling" the platter.
Every acceleration of the platter will degrade sonic performance due to very tiny flutter.
After starting the spin, once the platter is on the correct speed, the job of the motor/drive is only - IMHO (and very well backed by Newton and the laws of physic in the Einstein-continuum in which we still are (but don't really know for how much longer - given the latest discoveries in astrophysic science ..)) - to prevent the platter from slowing down.
Not to control it.
This leads to the principle of controlled slippage in conjunction with huge inertia which so far has not been applied to analog audio in any correct way ever.
Mostly because it is very expensive to do it right as it requires huge masses, very precise tooling and - if one want's any convenience in terms of getting to speed within a minute - very expensive motors.
I am neither in the BD nor in the DD camp and not in the ID (idler drive) camp either.
These all have their merits - no question about that.
And we will always see one or the other principle being en vogue due to fashion and style.
These 3 will always be what is available to the public.
But non of these is able by nature to provide the last 1% in performance.
By using one of the 3 common principles in tt-design, we always accept that the last "degree of freedom (here: sound w/o flutter)" is not with us.
Cheers,
D.