The problem isn't driving the stepper...
We already KNOW a UNO can handle a couple of steppers at the same time, perfectly well.
The problem is the mass of data from the camera. All that data must be processed to find the points.
Not that it matters. There's no mention of what kind of SW they're using at all. All they have are some CAD files.
Frankly, the entire Diwo site worries me. It's not really possible to find anythng in a logical manner.
(Yes, I checked it on GitHub)
Incidentally, they're using a USB-based webcam, but the UNO isn't an USB-master, so it can't control the camera.
The Atlas uses a Pi B+ or 2, which isn't all that more expensive, and the 5Mpixel is MADE for the Pi, so is directly supported.
The Pi Cam not only has a larger resolution(The Logitech c270 is a 3Mpixel camera) but it's also cheaper than the Logitech.
Weird guy...
Shapeoko 2014F: 1000mm X/Y, 300W Quiet Cut spindle, Arduino Uno/G-shield and GRBL 0.9i
15x30 drag chains, custom spindle mount, 9mm belts, 8mm endplates, 6mm motor plates.