Unrivalled in quality? IMO quality was one of the only bad things about the Nexus phones. 2 people I know switched to iPhones permanently after the constant issues they had with their Nexus 5s.
The Nexus 6P seemed high quality, I'll grant you, but the batteries were absolutely appalling. Mine would regularly die on 60%, or just on a cold day.
Are we forgetting the countless issues the Nexus phones had? The 5 for instance had bad camera quality and battery life even for the time, the speaker was as loud as a whisper, the side buttons would stick with less then a year of usage...
I had a 5X. I loved it, never noticed issues like you mentioned. 18 months later it got stuck in a reboot loop, took it back. Known issue, have a refund.
I used a 5X for a year and a half for free. Best bang for buck I've had in a phone.