A central clock source was considered essential in the 80s, and since then getting less and less vital it seems. Early phase lock loop systems were crystal based. Now PLL technology is capable of much better accuracy, but to answer your question - do they all play at different rates? Yes I suppose they do. Is 44.099KHz rather than 44.1KHz important? I've noticed that when syncing video tracks, each new camera seems more stable. I can now run two cameras for 2 and a half hours and not have to re-sync them in the edit. Direct to card recording. Tape based digital always drifted a little, yet the sample rate was, on paper, exactly the same.
They do differ, but how much matters before whatever you are doing doesn't work?