Designers of wheels, boilers, mechanical linkages, structural components, blades, and so on have always been limitedly the states of the art of materials and processes of their times.
The stone age gave way to the bronze age. Then came iron and then steel and then other metal alloys.
The predominant methods used for manufacturing parts from things such as rolled steel or steel ingot or bar stock were casting, forging, extrusion, and cutting (metal removal). Each had its advantages and disadvantages. For low cost applications not requiring precision or long wear, sheet stock could be pressed or otherwise formed to shape.
Designers were limited to the materials available; to part shapes that could be made using the aforementioned methods; and to the use of assemblies made by putting together individual components that had been so manufactured.
That was fine. That was what they had. The Colt 1911 was a good design, and so was the J57 engine.
Then some new materials came along. And new methods of making things, far too many to discuss. Individual part designs could be combined into large, complex, integral pieces never before possible.
A designer today is not limited by the materials and factory machines that were available in the Colt factory in 1905.
No, designers today have much, much more latitude in making things mechanical.
Now, if what one wants is a 1911 pistol, a big Hand Ejector revolver, or a Parker shotgun replica, steel forgings and machinings will suffice perfectly.
In fact, that is what one would want, after hashing out a few decisions on MIM parts.
But one wants the best functionality that the designer can provide, it would not be a good idea to tie the designer's hands just for old time's sake.