Owning a BM-59, a couple M1As, and a few M1 Garands in both .308 and .30-06, I'd choose them in the same order if I had to carry one in combat.
Italian tactical doctrine immediately post WWII is what it was. Remember, they were transitioning from the semi auto 8 round en bloc clip Garand, which they were building on Winchester's M1 Garand tooling they acquired through the government (prematurely as it turned out given the unforeseen Korean war).
While they saw the need for a 7.62x51 rifle beginning with their 7.72x51 Garand conversions, and also saw the clear benefits of having a 20 round box magazine, especially in a rifle designed to accommodate an optional M2 Carbine style select fire capability, they still didn't see a need for a large number of magazines to be issued with a BM-59 set up and issued for semi auto only fire.
Keep in mind you have to carry that ammo, as well as those extra magazines. BM-59 magazines are heavy. They weigh 11 oz empty compared to 8 oz empty for the M14 magazine, and just 1.2 oz for four five round stripper clips. Northern Italy is very much alpine and weight is very much a concern in that environment.
Also consider for a minute that two double magazine pouches were standard in US service for the M14. The Italians would provide a single double mag pouch and two magazines for the BM59. In both cases, all of the remaining ammunition was carried in stripper clips. Bandoleers were used in the case of the M14, while the Italians used bandoleers and/or a Garand clip belt for the BM59.
Like the US military, the Italians did include clip guides to use stripper clips to recharge magazines directly when they were not in the rifle. Like the M14, the clip guide in the receiver was a contingency to quickly top off the magazine before it was empty.
In short, the Italians were just more likely to use the clip guide in the receiver if suitable circumstances arose rather than run the mag dry and swap it out.
"BERETTA BM59 AND ITS SEMI-AUTO VARIANTS.."
The Free Library. 2018 InterMedia Outdoors, Inc. 16 May. 2025
https://www.thefreelibrary.com/BERETTA+BM59+AND+ITS+SEMI-AUTO+VARIANTS.-a0546960022