Q.Why Is My Rubber Tree Growing Bark Faster Than Leaves?
The stalks of my rubber tree have turned to bark fairly quickly. Each of my five stalks grew 3-4 leaves this year, and yet the bark growth has significantly out paced them, leaving only 2-3 leaves on each stalks. (As the bark creeps up, the leaves on the bark drop) it seems otherwise healthy other than *mildly* curled/droopy leaves.

Certified GKH Gardening Expert
You may be overwatering. Also check for insects such as scale (which could look like bark). These articles should help pinpoint the problem.
https://www.gardeningknowhow.com/houseplants/rubber-tree/rubber-tree-plant-leaves-falling-off.htm
https://www.gardeningknowhow.com/houseplants/rubber-tree/leaf-curl-on-rubber-plants.htm
https://www.gardeningknowhow.com/houseplants/rubber-tree/yellow-rubber-tree-leaves.htm
https://www.gardeningknowhow.com/houseplants/rubber-tree/how-to-care-for-a-rubber-tree-plant.htm