If phone manufacturers stopped producing 10 models every year and focused on making a single robust one, they would have plenty of resources left for actual maintenance.
Sure, but they're in the business of selling as many phones as possible which means getting you to upgrade every so often. Unless they settle on a business model that allows them to make money from your old phone, I see this continuing.
Honestly why should I care what their business model is, if it is detrimental to users and the environment. That's the whole point of laws, to discourage behaviour that we as society deem undesirable.
"Selling as many phones as possible" allows yearly upgrades, but instead of 10 different models per year they can sell 3 models per year with 3.3x sales of each model. I am looking at Samsung models on the market, they are close to 10, Apple has maybe 2 or 3.
How so? Apple also releases new models almost every year with very dubious quality. I remember some scandals about antennas, and more recently about RF interference with pacemakers, but i'm sure there's a lot more i'm unaware of. Apple prevents users from using the hardware however they please and blocks the bootloader. They don't even give you root on your own phone!
Also they're famous for making their products hard to repair. It's hard to find spare parts, hard to find their custom screw heads, and hard to tear everything apart. You can't even remove the battery without tools which is very user-hostile, bad for the environment, AND was a pattern "popularized" by Apple, because if any other hardware manufacturer had dared to do that, they would have sold exactly ZERO phones.
All in all, Apple is close to the worst manufacturer i can think of to get inspiration from, although on specific topics (eg. LCD screen solidity) they are definitely not the worst.