That's not accurate, at least in the United States. Product warranties are issued by manufacturers, and Google's pages for TP-Link[1] and Asus[2] confirm this.
The manufacturer warranty is 2 years for both the TP-Link[3] and Asus[4] OnHub models.
If there were a class action, it would be against TP-Link and Asus. These manufacturers would then take the losses into consideration before collaborating with Google in the future.
Yes, maufacturer warranties are not implied warranties. They are explicit promises from the manufacturer to repair or replace products that fall below certain standards within a period of time.
For example, the TP-Link limited warranty explicitly identifies TP-Link USA Corp. as the warrantor:
> TP-Link USA Corp. (“TP-Link USA”) provides a limited warranty on all eligible TP-Link products purchased in the United States.