Just remember: it's YOUR FACE that's directly behind the slide when the round fires.
I saw the results of a pistol frame (brand withheld) rear section breaking off and allowing the slide (or part of it) to strike the shooter's face.![]()
...and other parts can fail as well: at least one Beretta 92 slide failed during US military testing, and hit the shooter in the face. Ruger very famously tested the P85 beyond anything that would be encountered in the real world (which was one reason I always liked P-series pistols :^)...