Sure, but which higher-end (excluding, eg, cheap toys) rechargeable battery powered electronics device do you expect to last only two years?
Of course, some of the fairly drastic reduction in battery life after only two years is a conceptual issue that the Airpods probably share with other wireless earbuds that come with a charging case. The much larger battery in the charging case allows for a very small battery in the actual earbud as the latter doesn't have to last a full day. You thus start with a fairly low battery life of the earbud itself that when maybe reduced to 50% of original capacity becomes annoyingly short. Moreover, given that one might recharge the earbud multiple times per day, it accumulates charge cycles significantly faster than wireless earphones that provide the full day capacity via their built-in battery.
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Apart from some variation in battery production (ie, each cell or each batch might turn out slightly different), one side might have a less restricted wireless path to the Bluetooth host device (ie, iPhone) and thus require slightly more power which results in slightly more battery wear.