Joined: Jan 2010
Posts: 9,805
Likes: 1,772
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Certainly the crimped stays are also electric-resistance-welded or brazed to the dropout tabs, so should be reliable.
DiegoFrogs, what you called (derailer hanger) sounds like just the dropout(?).
And yeah, the entire dropout, top and bottom of the slot, are highly stressed in use, so sometimes fail anywhere along the load paths from the axle to the stays.