Not sure what you mean by design, tearing isn't a design feature, it is an anomaly which happens when frames aren't synced to screen and can happen below or over refresh rate. I don't think you meant it this way though, it's just how i read it.
Tearing is more noticeable when frames are over but sometimes people think tearing is less when frame rates are closer to an even ratio or refresh is sort of quick enough to make it bearable. Ie 120fps 60Hz or 140fps 70Hz, with every 2nd frame giving the appearance of being smoother but there's still missing frames the screen was unable to refresh in time.
Purpose of variable refresh monitors is to display frames as they happen from the gpu instead of using a fixed refresh rate and vsync to minimise input lag.
There's different Vsync types to try help tearing but if you're happy with how things are then that's fine. To view all frames your gpu is capable of dishing out, the monitor needs to be able to keep up. If Vsync input lag is an issue there is a trick you can try by limiting frame rate 1 below refresh.