Wife uses a mid-2013 Macbook Air as a daily driver still after >10 years, works in academia. What happened is simply that CPU stopped being the thing that made stuff slow, so a mid-2010s upper midrange can still hold its own today, ssd was already good then, and memory plateaued around 8gb for entry level machines some 5 years ago. So as long as your thermals don't suck, your ssd doesn't smoke out, and your keyboard holds up, you can still use these machines today. If you maxed out memory then, that is.