Exactly! That's what I've been saying, and it is why basing the ID on the strap is a very bad idea.
If we came up with a revised rating system, where the strap is just one of the rating elements, that could, possibly, address the issue without invalidating a lot of IDs.
This watch, for example, could stay a "Q", which it most likely is, with one less checkmark for the missing strap. If an ad came along later that showed the "Q" with this particular light brown leather strap, then the watch would get the final checkmark. If an ad came along later showing this watch with the leather strap as an entirely different model, then we could change the ID and congratulate ourselves for having recognized via the missing checkmark that the strap could, and did, matter.