Zamac gets a really rough deal, one that is certainly not deserved based on reality.
Gillette started using Zamac for razor heads about the time of the Korean War. Quite a few of those Zamac razors are still around, still being used and still looking good. Those razors have lasted over a half century. I have some. I use them. They have been treated just like my brass or steel or any other material. They work as well today as they did a half century ago.
In this picture the middle razor is definitely Zamac and the one on the left is almost certainly Zamac and I have another English Tech with a Zamac head and all the faceted head Gillette razors were Zamac heads IIRC.
Zamac works. Is it different than steel or brass or plastic? Yup. Is it worse than steel or brass or plastic? Nope; just different.
If someone does not want to buy a Zamac head razor, fine; but let's not pretend that it is a decision based on some quality claim.