Not true. The case mouth is only a limiting factor. Your 10's still space off the extractor, unless the case is long enough to hit both (about 1.002"). As the slide/breach picks up a round from the mag, it slides up the breach, and under the extractor.
But, if that's what you believe, precede. The extractor was never designed to hold the case against the breach face although shooting the short cases takes advantage of the extractor to breach dimension relationship. Possibly the manufacturer should just eliminate the final machining of the shoulder in the chamber altogether under the premise that it is unnecessary. I mean, there is no need to regulate case length and the COAL length could be limited by the rifling in the leade.
When I see Glock (or any other manufacturer for that matter) say that it is acceptable to shoot ammunition in any gun for which the gun is not chambered, I'll buy into it. Until then, this is a totally false economy and any body who does this is totally on their own if something bad happens.
Oh, incidentally, the "no reloads" argument doesn't hold any water because the reason for it is totally different.