Traditional frame swap goggles can make sense if you're budget-conscious and willing to swap lenses at home before heading out, not on the mountain. You simply flex the lens in and out of the frame, but it takes patience and careful handling to avoid scratching or damaging the lens—especially with cold, stiff hands.
The big trade-off is convenience. Unlike magnetic or clip systems that let you swap lenses on the lift in seconds, traditional frame swaps are slow and frustrating mid-day. If the weather shifts from sunny to flat light, you're stuck with what you have unless you head back to the car or lodge.
If you mostly ski in consistent conditions and just want a spare lens for storm days, this system works fine—just change lenses before you leave. But if you regularly deal with variable light and want on-the-fly adaptability, save up for a quick-swap system. It's also smarter to buy one goggle with an excellent all-around lens than a cheap interchangeable pair you'll never actually swap.