You are limited with pre-fits when you buy off the shelf ready to go pre-fit barrels: limited to certain barrel companies, limited to reamer/chamber designs, etc.
If you buy a shouldered barrel from a gunsmith, you really have any combination available to you. You can use the top tier barrels: Krieger, Bartlein, Hawkhill, Benchmark, Rock Creek, etc. You can use any reamer design available - tailor it to your needs and components to extract the ultimate precision, rather than being limited to generic SAAMI spec designs.
Sure, a gunsmith can spin you up a pre-fit with any of the above, but then it loses that so-called time advantage over a shouldered barrel. And you would still have to deal with that ugly barrel nut and go/no-go gauges. Most gunsmiths will tell you that if you are after ultimate accuracy potential to go with a shouldered barrel, but I will say that some pre-fits can shoot really good.
I like that I can call up my gunsmith have a shouldered barrel spun up with any barrel make, contour, reamer, length, etc that I desire. I can spin it on in less than 2 minutes, and the zero will not be off by more than 0.1 mils of my other shouldered barrels.