Strained nanomechanical resonators have recently achieved quality factors of 1 billion through the phenomenon of dissipation dilution. Remarkably, the potential of these devices seems unexhausted, exhibiting a scaling law of roughly one order of magnitude (in Q factor) every three years. This paper reviews advances which led to this point, including phononic crystal "soft-clamping," strain engineering, and a trend towards centimeter-scale devices with extreme aspect ratios. Recent trends include investigation of strained crystalline thin films, fractal-patterned supports, and machine-learning-optimized supports. New possibilities emerging from these advances range from cavity free quantum optomechanics to ultra-sensitive accelerometry.