Devices do occasionally shop with bad batteries. I'm not sure why you double-quoted 'normal people', is this some weird attack on people who cannot use google and a screwdriver?
The prevalence of batteries on Amazon suggests that there are a lot of people who replace batteries in devices. I can only speak for myself, but if iFixit says a repair is ten minutes using standard tools then I would go the replacement route. People who cannot afford a new controller, or would use prefer to spend money on something else, will probably work out swapping the battery is an option.
Fixit's business model is predicated on a lot of people wanting to repair things, not replace them.