Steering All Over the Place at 55mph+

I'm not trying to start an argument, just asking a question. What about the early A bodies? They only have one idler arm tab too. If it was such a bad thing, wouldn't we be seeing lots of failures? I've never seen even one. What about the 67 is different or worse than the early cars?
The one in my 67 was VERY VERY bad, but the present issue is that they are hard to get (one year) and VERY expensive