Yes wow, because it’s not the norm. Before I switched to an iPhone, I needed to change my Android phone every 2 years or so (sometimes less) because they became completely unusable, from hardware issues (broken connectors) to software issues (I had 2 Nexus 5x that died because of a bootloop issue, unacknowledged by Google). Android also becomes extremely slow pretty quickly for some reason.
For comparison I’ve had my iPhone 12 for 3,5 years and it shows no sign of slowness or battery issues or whatever, and I intend to keep it for at least 1 or 2 more years. When OP say it stays functional for several years, they mean it stays as functional as the first day for several years, with no degradation.
You would have had the same experience staying on Android. I used to switch Androids every ~2 years, but I've had my latest Android for >4 years and feel like I've got several more years in it.
For comparison I’ve had my iPhone 12 for 3,5 years and it shows no sign of slowness or battery issues or whatever, and I intend to keep it for at least 1 or 2 more years. When OP say it stays functional for several years, they mean it stays as functional as the first day for several years, with no degradation.