That's not a problem if you make sure to have them train their replacements a few seasons before they go all sideways.
Ultimately, I think we would see the attitude you propose, but if half of the Magi have that attitude and half don't, the half that dosn't is going to have more free time, more resources, more magic, etc. Up and coming apprentices will look at these two groups and go "Screw that, I'm letting mundanes do the work."
Well, I don't think we have anywhere close to half the magi thinking mundanes are good for handling the most valuable things magi own....
Also, I tend to think covenants are fairly isolated... yes, they get visitors but most apprentices are not going to have visited alot of other covenants unless their parens happens to be very political or social. The fifteen or more years learning "The Fengheld Way" are going to have a lot more impact that a few days or weeks at a different covenant (in general, obviously that not an absolute).
Its really just a flavor thing and that's personal preference. Frankly, you could make some sort of magical duplication item that would be even better since it won't go catatonic from warping, doesn't need to be paid, and shouldn't need to be replaced.... The troupe just needs to decide where they are most comfortable with the line being drawn. I like Hermetic books to be rare, valuable, and too precious to entrust to the hands of lesser beings. Others prefer them to be more commoditized.