I have frameless cabinets in a 2nd small kitchen and 2 bathrooms. The kitchen cabinets are only 3 years old, but the bathroom cabinets are over 10. I have never had a problem with the cabinet faces.
I have framed cabinets with partial overlay in the main kitchen. I hate that post in the middle and the wasted frame space on drawers.

Maybe the specialized equipment helps you stick the veneer on hard enough it doesn't delaminate? I've got frameless cabs, from '91, and they are not doing this. Flip side, my desk at work, the edge trim is delaminating (this isn't cabinets, of course). I've put edge trim on a number of things when woodworking & it's not super easy, but it's not rocket science either & I've never had things come off from that.

The KD is making things up as she goes along, or fell for the line that the cabinetmaker fed her.

You should be dealing with people who know more and who are honest about it.

On some of our projects early on (before I knew better) the cabinet maker would use a veneer edge that was the same species as the cabinet doors, or a veneer edge that could be painted if the door were to be painted...and they would then stain (or paint) the edges before putting the boxes together....I would say the edges done this way were very fragile and prone to chipping etc

Now we insist on all edges of the boxes to be banded with a 1MM PVC banding that is a "close" match to the doors of the cabinets. I say close because there is not always a perfect match in the PVC to each and every stain or paint color....but have found that there is always something that is extremely close and has never been a problem

The PVC comes in a couple different thicknesses, we have found the the 1MM (millimeter) works extremely well and have never had a problem with them

Hope that helps

"Is this really a concern for frameless cabinetry?"

No.

On the one hand it doesn't need to be a problem, on the other they ate still likely telling you the truth based on their experience.
In a small shop, even if they have a panel saw, material is still handled extensively by humans. It is easy to end up with a less than perfect edge when cutting sheet goods. A small imperfection is an opportunity for a poor connection or a weak spot for veneer to crack.
Ajc's solution is ideal in that case.
Move to a larger facility, where panels are moved into place mechanically, with perfectly aligned saws, edges can be cut perfectly. My hi-end brand, while fully custom, uses that type of equipment for sheet goods. They use a wood veneer edge, ive not had a problem.
That said synthetic edges, as ajc suggests, are quite acceptable. On Frameless they are barely noticeable. Have them in my own home, 9 yes now.

jakuvall I am curious what manufacturer you are referring to when you say your "hi-end brand"?