Can a Quality Full Range Speaker be the Limiting Component in a system?

MHO...no.

The physics of the speaker preclude 'accurate' reproduction over a bandwidth that relates to the range of human hearing.  Now, by 'accurate', I'm referring to a 'ruler flat' line that would appear on a piece of test equipment.  These devices Do Not Exist.  If they did, we likely couldn't afford them, nor would we 'like' what they sounded like...IMHO....

We're so used to the 'coloration' of the various drivers available, and that of the equipment and hardware that we employ with them, that 'accurate' exists in the mind and ear of the beholder...IMHO.

Note that I haven't mentioned the space in which an audition would occur.  That's an entire issue unto itself....

All of this reminds me of the 'ideal pulsating sphere' as a reproducer....which leads to a plasma 'driver'....which is only practical if you don't mind not breathing or fouling the atmosphere on a regular basis...

To be fair, I like the concept of the full-range single driver.  But, most of what I've seen and heard is still short of the goal due to simple mechanical and acoustic 'fail'.

You 'can't get There from Here.'  You might get 'closer'...but No. 

Sorry...

soundsreal, and y'all....instead of thinking that speakers are a limiting factor (unless they Are utter dreck...*L*), I like to approach them as having different 'voicing', much like us....  Anyone can, say, read Shakespeare out loud.  But the numbers diminish as expression, timing, and nuance get expected at the presentation

With that in mind, it begins to make sense, the inexpensive speaker that outperforms pricer ones....the 'sonic surprises' that extend into the 'driving equipment, for sure, but speakers make their 'differences' known sooner, being so 'elemental'....