The devices definitely last, I have plenty of decade+ old devices that do still work. The issue is if the battery swells, it takes out the device with it quite often. The one swollen battery was a Blackberry Passport in otherwise perfect condition. The battery swelled, cracked the screen and tore a ribbon cable, this was long after BB went out of business. I'm still sad about it, it was such a cool device.

Regardless of swelling though, once a battery can no longer hold a charge some devices become functionally useless. For example I have a number of old handheld consoles, fortunately batteries are still being produced for them, but once they stop the device will be useless. With how great emulation is and all the new emulation handhelds, I'm really not interested in playing my GBA SP or DSi tethered to a wall outlet.

For laptops in particular yeah they have plenty of uses, especially a "4 year old" laptop, that's still quite good hardware (unless it's e-waste at production, like chromebooks with soldered storage and RAM). But it's not gonna be a laptop anymore, it basically becomes a desktop / server etc.