Earlier quoted context omitted.
Not sure what your definition of gray market is, but there wont be any warranties usually...
He's saying warranties are mostly useless on watches.
A decent new watch isn't going to have a defect. The parent referred to a theoretical $500 watch. Let's take something like a Hamilton Khaki Field Automatic. Decent watch, very handsome, and usually comes in around $500 (or less).
Hamilton is a Swatch Group company and gets the very, very popular ETA 2824-2 movement. This is the same movement that can be found in watches costing thousands and some times tens of thousands.
The quality and the internal components are the same. More expensive watches sometimes get nicer finishes on the movement and occasionally get a COSC certification, but by and large, there's little difference.
ETA has been making the 2824 since 1961. It is the workhorse of the watch industry. I've literally never heard of a defective one that wasn't a clone.
So, I'll personally guarantee that your $500 ETA 2824 will run for five years without defects at which point it'll probably need servicing, i.e. cleaning and re-lubrication. That's going to cost $200-300 from any Swatch Group authorized service center regardless of whether the watch has a warranty or is grey market.
Anything much cheaper than $500 is either going to be a Miyota or Hattori movement or a clone of a Swiss movement. I'd consider those watches to have a finite life span of a few years. Likely they'll not be worth servicing when the time comes, though there are definitely exceptions.