Once upon a time HP built computers and printers like Mack and White Freightliner built semi tractors. . . Metal parts. . . Metal and Nylon gears, the only plastic was outside on the case. That was when you needed a Mack truck to move a printer amd many computers. Remember ten pound laptops? Now, everything is plastic except for a few rods and springs and even some rods and springs are getting plasticized.
Warranty repairs are a cost included in the bill of materials of every product made, and the length of time it will be covered is part of that calculation. Increase the length of the warranty, as did the EU, and the price of the product has to go up. TANSTAAFL! Someone has to pay for the parts and labor of warranty repairs. That cost is amortized over all units of each model sold and reduces the profit margin on the product when sold or increases the retail price. They calculate it to the penny and are usually quite accurate using historical experience. . . But it is always their best professional guess. They also include the guesstimated cost of consumer lawsuits. They have to.
Frankly, I saw more laptops with multiple missing key tops (why should so many keys just spontaneously pop off, especially keys that were not keys frequently used?) that made them unusable and lower cases splitting (users swear they did not drop them) than broken hinges, but also some with just floppy hinges where the friction no longer kept the screen in place. The other likely failure point was power jack ports, usually applied with only two extra mechanical solder dollops plus the actual power input solder points instead of screw connection mechanical strengtheners.
Commoditized laptops have to fail at a known rate. The business model of the industry demands it. The manufacturing/selling company requires more sales to remain in business because their margins are far too narrow to survive without repeat sales every so often, at least every two to three years. So, either the keyboards have to fail, the hinges, the logic board, or power supply has to die an economically justifiable, non-repairable death, requiring a replacement. . . Preferably with one of their own brand, but they really don’t care if it is.
Being a commodity, if their customer doesn’t buy the same brand again, some one else will jump ship from another brand to their brand just as easily when his old one died an equally justifiable, non-repairable death. It’s a game in commodity computers where brand matters less than OS, just as in commodity Android phones.
Thank you for the very good explanation. All of us our very fortunate to have you participating in this forum. And yes every repair you mentioned has afflicted laptops that I have owned or worked on. Some of them I have refused to let die long past the point where I should have given up on them.
My recollection of heat related failures is skewed because I tended to try to get a little too much performance out of of my laptops by using them for photo and video editing at a time when it was really better to do that type of project on a desktop machine. When processors were still socketed on laptops I sometimes put in a more powerful one when the prices dropped, which could increase the demand on the cooling system. I had one Compaq laptop that I replaced the motherboard several times on. Some surface mounted components would heat up to the point where they became loose. I was sometimes able to solve this type of problem with a heat gun, but usually this was just a temporary fix.
Of course power supplies would die frequently from operating at too high a temperature for too long. And the power supply jacks still get broken frequently by people who accidentally get tangled up with the cord.
But as you say the major brands all sell so many commodity type laptops at low enough margins that they have to be very aware of the likely failure points to help calculate how much that they have to sell them for to make a profit.
One of the most maddening issue to me is when the pcb board on a nearly new hard drive fails and the actual platters are perfectly healthy, but none of the manufacturers will sell a matching board or supply the software necessary to rewrite the ROM or even just send the command to reset a corrupt NAND on a hybrid drive. If you want your data back you generally have to pay a lot of money to recover it even if it takes a technician just 5 minutes to send a reset command, or replace a couple surface mounted diodes in a protection circuit. It is almost as bad as ransomware in certain situations.