Apples and Oranges.
Alternators are more efficient,lighter, produce more at lower RPMs and can be spun faster. So, in 1961 Chrysler started installing some.[ first I saw anyway]
We all know generators were being phased out in the 60s. They are older technology, heavier, less efficient, etc.
So, would I install an generator on a 60s or newer vehicle that came with an alternator, nope.
Conversely, would I install an alternator on an older care that had no idea what an alternator was and had never heard of one. Again, nope. A generator can be repaired inexpensively and made as 'bullet-proof ' as anything can get, especially with one of Toms EVRs.
There may well be a reason for someone to put an alternator on their 'A'. After-all its their vehicle and in this country, for the being, they can do as they please.
But, to me, that just ain't right. Thats my opinion and for right now I'm sticking to it. Of course we know what my opinion is worth.
Oh, I've also repaired a whole lot more alternators than generators which stands to reason just by looking at them.