Planned obsolescence / failure of consumer electronics / kill switch
I've worked on countless consumer products, and I've never seen a "kill" circuit that intentionally causes the product to fail after some specified period or event.

However, consumer products are designed for a certain lifetime, with a certain number of failures in that lifetime being acceptable.  That's just a reality of the reliability of components.  

The manufacturer has to balance lifetime and reliability with cost, product size, time to market and other factors.  If the product is too expensive or big compared to the competition, no one will buy it.  If it fails to early and provides a bad customer experience no one will buy the next one.

So in general manufacturers try to make a product as reliable as possible while meeting all the other product constraints.  What you hear about or remember is the time the product failed right after the warranty (or battery or whatever) expired.  The hundreds of products you have had that didn't do that don't get any "press".

If a battery is not replaceable even by the manufacturer then it may not make economic sense to make the product reliable enough to outlast the battery by a wide margin.