I've been reading back and thinking a bit about both Bob and Richard's comments.

The thought occurred to me that what we've been talking about could be related to instrument quality.

For the sake of my point you need to consider the voice as an instrument:

Any musically talented person should be able to learn an instrument. The harder they work the better they will get at their chosen instrument, but a time will come when the limitations of the instrument will limit further improvement.

Thus you get "student", "intermediate" and "professional" grade instruments. If I may digress into the brass world for a while as what expertise I have is grounded here:

Student grade instruments are usually built to wider tolerances in order to reduce cost. They are often heavier guage brass to help them take knocks a bit better and there is less choice in options. They come with a "standard" mouthpiece and usually include a fairly robust case.

Professional grade instruments are built to much closer tolerances (price is usually much less of an object when compared to performance). The guage of the brass is often lighter, though not always - this depends on the sound you are seeking. You will have options in alloy's available (Nickel silver, yellow, gold or red brass - raw, lacquered or silver plate etc.). They won't come with a mouthpiece as you are expected to already have a preferred one. They often don't come with a case as many pro's prefer to use a gig bag (I don't, but then I don't make a living at it either).

Intermediates or "step up" horns fall somewhere in between these.

What this means is that once you reach the limits of your instrument, you have the option to (try to) purchase a better one. Sadly singers don't have this option - if their voice is ordinary, then that's what they have.

However, training and practice - work - allows one to maximise one's results. Put a poor trombone player on my nice new custom Rath and they'll still sound just as bad. Put a good trombone player on a student horn and thay'll make it sound great. But it still won't be as good as when they're on their pro. horn (though they can surprise you sometimes...). I have several 'bones of various kinds and quality. The latest (Rath R10F) is by far the easiest to play. Now, I get "my" sound no matter which horn I'm using, though on my Besson (which is closest in bore and bell specification to my Rath) I have to work much harder to get a similar result to the Rath. The Rath is easier to play... I'm sure you find a similar phenomenon with your guitars. Body shape and stiffness, pickups, angle of the neck, string selection, the action &etc.. The better the quality, the easier it is to play.

The same applies for singers. A well trained singer with a poor voice can sound pretty good, a poorly or untrained singer with a good or great voice will potentially sound pretty good too, but to actually be good or great they will still need training and practice. They just get to start with the "pro grade horn" instead of the "student model"... In other words, "It's easier to play"...

--=-- My credo: If it's worth doing, it's worth overdoing - just ask my missus, she'll tell ya laugh --=--
You're only paranoid if you're wrong!