I have a 3GS, a 4, a 4s, a 5 and a 6s+. My primary phone is an 11 Pro Max.
Between all of these phones there is one issue. The iPhone 4 has a faulty power button. I bought it for $20. I'll give you batteries, although my 3GS seems to do pretty well. I got that one for $25.
The 6s+ is my secondary phone. It too six years for the battery to degrade enough before Apple would replace the battery. That was November 2021. It does just fine with battery every day, although as a secondary phone I'm not using it much.
I suppose if you're using a phone for more than what I use it for (calls, texts, light email, light web browsing) then you could be right. On the other hand, the 3GS, the 4 and the 4s were never my primary phones. So I have no idea how the original buyers used them - yet they are still functional.
And I don't handle any of these phones with kid gloves, I just take care of them.
Oh yeah. My smartphone from 2009 (HTC Touch Pro) also works perfectly. That's running Windows Mobile 6.1. And my Pixel 3a XL, bough in May 2020 is fine too.
I think it depends a lot on how much daily screen time those devices get in their lifetime.
A lot of younger individuals (mainly those born in the 2000s) use their smartphone as their only computing device until they're in college, so those phones get a lot of additional abuse.
I have an iPhone XR in my household used in such a scenario, bought around mid 2019, the battery is cooked and the touchscreen is on its last legs, starting to glitch occasionally.
It's likely to be trashed after replacement but it's fine as the user has got a lot of mileage out of it.
As for myself, I use the smartphone as my main GPS (both on foot and while driving), it handles my home banking, various digital IDs, picture/video taking, multiple WhatsApp accounts, I used to upgrade every 18-24 months (Android user) by reselling the old one, but starting with the S21 Ultra I can no longer find a solid reason to do it.
Also I have to say that hardware durability has massively improved in the last years.
Batteries last longer, screens are a lot harder to smash, and also I've never seen an USB-C or Lightning connector break.
That used to happen all the time with the old 30-pin iPhones, and also when microUSB was a standard, if you often used your phone while charging, it would eventually break in a matter of 2-3 years.
Nowadays they look indestructible to me, as long as you buy iPhones or Samsung S-series.
Budget Motorola or Xiaomi are much frailer, mainly on the screen part.