Whats the big thing behind? Speed and weight for a start. Multiply the two to get momentum. A jet is not a prop and if you don't manage the energy early there's no way to get rid of it later, especially if you're in a lightish jet with thermal anti ice causing a high idle setting above your normal approach idle. The big jets operate at a whole new level of aerodynamic performance too. A 744 at max weight will leave you about 10-15 knots of airspeed to fly in whilst cleaning up in an aircraft that wallows and is highly G sensitive. Yank the controls and watch the barbers pole rise like a shot - low speed buffet is not a nice place to be on one of those things.
I think you are confusing the issue with your reference to the MD80/DC10 convertees. Struggling to convert to an EFIS environment has nothing to do with the ability to fly a jet or a prop. There are plenty of people who've struggled with converting from a 737-200 to an A320 as well, doesn't mean they can't fly. You'll find you also get plenty of non-precision approaches in the jets as well, into some surprising places like FRA and JFK or DME. Trying to pole a heavy jet into one of these places whilst contending some pretty shocking ATC, some of the worlds busiest airspace and interesting Russian altimetry is rather more demanding than you might imagine and requires a higher degree of accuracy than on a light aircraft because if you're tracking at the 5 degree limit of the NDB you won't be able to pole it over to the runway when you go visual.