Honest question about cartridge vs. turntable performance.

The primary functions of the turntable are consistently turning the platter at 33-1/3 rpm (stable accuracy) and doing so with little noise. It is the most critical component in the analog chain.

Right. All high-end Direct Drive turntables are the most stable in speed accuracy on the planet. This problem does not exist for DD owners. There is no issue with speed at all. Motor on Neumann cutting lathe is also Direct Drive and this is the first step in vinyl manufacturing process.

Turntable that can’t guarantee speed accuracy are junk.

Problems with speed accuracy associated only with Belt Drive turntables, but people loves them, don’t you see?

Chakster, as always there are conflicting attributes. Yes DD tables are some of the most stable. Most think that added stability is meaningless.
The Dohmann Helix turntables are belt drive and even more accurate.
It uses twin belts of different durometers and a drive system that will maintain the programmed speed regardless of friction, etc.
Having an oscillating electromagnetic device under a very sensitive electromagnetic device is a bad idea especially when the platter is paper thin. XactAudio's Beat turntable might get away with it as the platter has got to be 4" thick. Remember magnetic field strength drops with the square of the distance. Price is about the same as the Dohmann. I would take the Dohmann in a heartbeat. Dohmann is far more open about its design whereas the Beat is cloaked in mystery most likely because there is nothing patentable about its design. The Dohmann's MinusK suspension is patent protected. I also prefer suspended turntables. The Beat is supposed to be isolated but it is not suspended. I do not believe in magic.
The one saving grace of the direct drive turntable is you do not have to worry about belt wear. I figure if I can change the accessory belt on a 911, I can change a belt on anything:)

So Chakster, then why is it that the vast majority of the most high-end turntables are belt drive?  I welcome your explanation.  There could be something to learn from it.

And, per your comment, then my new Rega Planar 10 turntable is junk? I beg to differ as it sounds better than any other turntable I have owned, direct drive and belt drive units.  I am very open minded so, please, explain away...

why is it that the vast majority of the most high-end turntables are belt drive?

Its low-tech and easy to get good results?

I finished my country house turntable project - goal was to find small  good turntable.

So my choice at the very end is Era turntable + Ortofon 9 inch RS-212 tonearm + Aidas cartridge.
Very small and not serious looking. Sounds better than any Rega for me:)

But if to look into Era it's rather cheap belt drive engineered by Verdier. With very small motor and very loose belt. And very strange design I have to say. Although in my opinion Era don't make any sound it just keeps the speed with very low wow and flutter 

Then you don't see turntable sound is superb :) Although now I want for my home big Verdier turntable as it is more serious and it will look nice near Garrard.

Engineering is the key. Good turntable can be very simple. Does it means that it's the most important - I don't think so. But in the late evenings then turntable spins and shines it's the most important part in the system. That is for sure.