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The attainment of perfect collimation in a Newtonian is an ideal... but it is not necessarily a prerequisite for an an excellent visual experience. All it means is that the diffraction limited portion of the view is centred in the eyepiece field stop. You can be slightly off and still see a perfectly sharp image in the eyepiece (albeit with the sweet-spot de-centred). Refractors are different in that the magnitude of off axis aberrations are generally better controlled (mostly a function of the focal ratio) and the mechanical requirements of lens assembly necessitate an ota that stays orthogonal. If you were to throw $10k at a 6" newtonian you could also make it impervious to collimation errors.
To reiterate... the primary advantage that refractors have over any other optical format is that they scatter slightly less light across the image rendering what can be perceived as a slightly more 'pure' view.
However, I disagree with the maxim that implies that the merit function of refractors is intrinsically superior to reflecting telescopes as a priori. It simply doesn't stand up in the real world .... at all.
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