Laptops definitely get replaced when the battery stops holding charge, but typically that happens at 5+ Yeats not 3.
Sure after 2-3 years you still have some charge, but it's more like 1 hour when browsing the Internet and not the 6-7 hours that it had originally.
I might just be buying shitty laptops though. Do your phone batteries also last 5 years?
Below a certain dollar amount, the refurbish vs replace from a value standpoint changes quickly.