Crop is a value for money. Are there any advantages in viewfinder other than reach? If we are using the same lens (adjust for the reach by cropping), subject will be bigger in view finder of crop. More focusing points on subjects or bigger subject per focus point for tracking might be advantageous right?
It's still mainly overall cost. You're correct that using the same lens for a distant subject, more VF magnification and more AF points on subject are an advantage. But unless you're already at 1200mm (600 II + 2xIII), you're still talking cost savings. 600/4 on FF will beat 400/5.6 on APS-C. I suppose an argument could be made that the 600 II + 1.4xIII is f/5.6 and allows all AF points, so that on a 7DII vs. the 600 II + 2xIII on a 5DIII which gives just the center point with 4 expansion points. But at higher ISO (which are often needed at f/5.6 and narrower with subjects like BIF), the FF would deliver better IQ.
It's anecdotal, but lots of bird photographers who shot with a 7D then got a 5DIII/1D X soon switched to using the 5DIII for birds. Notably, that includes some people on this forum who'd done some pretty detailed testing to demonstrate the reach-limited resolution advantage of APS-C.
Besides cost (of camera + lens), there can be a size/weight advantage...but 7-series bodies are not significantly smaller/lighter, and with wide-to-normal lenses the differences aren't great.
On the other hand, if someone prefers wider DOF...will find more advantages in APS-C.
Sorry, but that's simply not true*. It's true that for the same framing, APS-C gives deeper DoF. So...you stop down the lens on FF and you get the same DoF. If you need to keep the same shutter speed, you raise the ISO and there's no difference in noise; if you can let the shutter speed drop, you get less noise on FF.
In terms of DoF, FF allows you to achieve shallower DoF than APS-C if you want it, or the same DoF without penalty if you don't.
*There's an exception, in that if your lens is stopped down to its narrowest aperture, APS-C gives deeper DoF because you can't stop the lens down further. But by then, diffraction will be softening the images a fair bit, and that will be worse on APS-C at typical pixel densities, so in that case you're trading sharpness for DoF.