I don't know how much you know about MPL, but where I come from, MPL students fly nearly as much on the real training aircraft as did conventional trained ones. The only difference is that:
- they perform airliner oriented training from the beginning
- flying is done in view of future two man cockpit role
- they only do 1 test for a license, that is the one at the end.
I fail to see from your post if you are against MPL only or against ab initio trained pilots. I agree that I wouldn't put such a guy right away in a long haul cockpit, but these guys (ab initio that is) fly around in major airlines for the last 4 decades. If you would be trainer in such an airline, you would be given a choise to fly with them or to quit.
I guess your preoccupation comes from the fact that your FOs always where very experienced GA or turboprop regional pilots. I have been ab initio, regional and mainline pilot so I think I can tell the difference.
I don't know where you are flying but also ab initios fly around daily in high density airports and they do a good job. Well, I don't know if you find them in JFK, LAX or ORD, but you certainly find them en masse over LHR, CDG and FRA. And I still have to hear of a report where they failed. imho PM (PNF) role in such environment is much more demanding than PF.
Dani