Aluminum guns are meant to be shot little and carried much.
Early Colt Commander's were that way, but S&W's aluminum receivers will, with proper maintenance, survive many tens of thousands of rounds of full power ammo.
Remember the old Miller Lite commercial?
Less filling!
Tastes great!
You are both correct.
BITD, even S&W admitted that the alloy framed guns would not likely be able to achieve the round counts of the steel framed guns, all things being equal.
Of course, in the real world, all things are seldom equal...
Maintain an alloy framed gun and it can achieve very high round counts.
Abuse a steel framed gun and it will fail early.
I was in the motorcycle business for 40 years and it is the same thing.
Harleys, Hondas, Triumphs, Yamahas, BSAs, Kawasakis, Nortons, Suzukis, BMWs, Moto Guzzis, et al.
Sedate street cruisers and all-out competition racers.
I sold, rode, and serviced them all.
Maintain them and they will last.
Abuse them and they will fail.
John