I think a lot of people want a new device and use the battery getting weak as an excuse to justify the expense
It's not that I'm not sympathetic toward wanting the new shiny. I've been there and done that and generated my share of e-waste. But I've managed to (mostly!) get off that treadmill. I only got a new phone last year because my old one stopped getting security updates. The new one will (in theory) be supported for 7 years, so, barring loss or catastrophic breakage, I should be good until 2031.
Surely wrinting better software will help. /s