In the 90s there was no software updates. It was just a phone, no updates to download nothing but a basic phone. Do you remember those times?
I think those phones were built to last. I still have an old Nokia with black and white display, no camera no nothing. But i bet its still working like new if i would charge and try it.
No need to say "better use your old Nokia then!" Its just interesting to think back on how everything changes. Sometimes old stuffs better than new regarding build quality.
You're confusing "build quality" with what you're actually looking to find. The phones can last just as long. But, that's not what you want. You want them to continue receiving software updates to add functionality in addition to hardware to magically appear within the device. That's not a conversation about build quality.
You're worried the device with become "obsolete" in relation to the other devices in the market. In that context, the old phones are far more obsolete. If we're basing "build quality" on this, then those phones have terrible build quality, by relation. After all, the phones that came after those phones were drastically improved. The phones releasing now are often with negligible changes that are more gimmick than function. If we apply your shortsighted definition of "build quality," it still doesn't favor your argument.
Here's the sad thing. You don't realize that by pointing out old phones couldn't be updated where new phones can that you're pointing out newer devices are built to last longer than older devices. You can either opt to maintain the same functionality you received before, and have it be no different than an older phone without software updates, or you can extend the "life" of your phone by adding more functionality. Either way, it's no worse off than the device you're pretending had greater build quality.