The article says that you can send it in to be recycled. Idk, but if you get a voucher for sending it in to use for buying the next one (or another product) people might actually do it and it is not as bad as throwing it away. A rechargable battery would also degrade over time and since it can only be a tiny one… Also there is a chance people might use it to tinker.

However, I agree that this design choice (resulting in the low price) is very questionable to say the least.

Naphtha (/ˈnæfθə/, recorded as less common or nonstandard in all dictionaries: /ˈnæpθə/) is a flammable liquid hydrocarbon mixture. Generally, it is a fraction of crude oil, but it can also be produced from natural-gas condensates, petroleum distillates, and the fractional distillation of coal tar and peat. In some industries and regions, the name naphtha refers to crude oil or refined petroleum products such as kerosene or diesel fuel.

https://en.wikipedia.org/wiki/Naphtha