For a number of product categories it means replacing solid metal parts with inferior materials, and that pretty explicitly does mean worse quality.
Have you used a 1960s KitchenAid mixer? They look almost identical to models that followed - but in the 1970s KitchenAid replaced the metal drive gear with one made of nylon on the consumer-focussed models, and now if you use one heavily, you'll have to replace that gear more or less annually.
The question is, does that prevent something worse from breaking? It's not inherently bad to have wear parts in a device, after all. Shear pins are a great example where you need to replace them, but something more important would break if it wasn't the shear pin, so it's worth it.
IDK the design of the mixers well enough to know if that's true for them, but I do wonder if that is the case.
> The question is, does that prevent something worse from breaking?
That is the stated justification, yes. However, in practice pre-1970s models will happily knead bread dough for years on end, and more recent models tend to explode within the first few times you attempt to make a loaf of bread (leading home bread makers to have to spend more on an expensive commercial model...)
> The question is, does that prevent something worse from breaking?
That doesn't matter if it means, for example, that my new mixer can't actually mix bread dough on a higher speed anymore (citing this as it's actually a failure mode on newer (like 1970s forward) KitchenAid mixers to the point that the manual mentions it).
That is an objective decrease in quality and fitness for purpose.
Lighter can mean worse quality, but it doesn't have to. For example, a whole lot of things don't need metal enclosures, and plastic can be molded into more ergonomic shapes too. Now, whether the plastic enclosure is made tough or super thin is up to the manufacturer, and of course most of them choose the more profitable planned obsolescence route.
It's hard to distinguish "worse because lighter" from "worse because planned obsolescense". Historically, both effects correlated in their introduction into design and manufacturing consumer products. Attributing everything to just once of the two is not doing justice to the actual mechanisms.
For a number of product categories it means replacing solid metal parts with inferior materials, and that pretty explicitly does mean worse quality.
Have you used a 1960s KitchenAid mixer? They look almost identical to models that followed - but in the 1970s KitchenAid replaced the metal drive gear with one made of nylon on the consumer-focussed models, and now if you use one heavily, you'll have to replace that gear more or less annually.