I have seen some people flatly state that it’s impossible to identify spiders without looking at the genitals. In fact, it is often not known how to identify spider species within a genus from photos alone, but it is certainly possible in the vast majority of cases. The tricky bit is that it’s often only possible to learn how to ID from photos by finding enough photographs of living spiders which were later dissected to confirm their identity. Photos of “preserved” specimens usually aren’t enough. In some regions of the world this work has already been done for most families of spiders, in others much work remains to be done before we’ll be able to ID from photos.
There are exceptions, where two or more closely related species are visually indistinguishable, but this seems to be relatively rare compared to the number of species which are visually distinct.
So if you run into someone who says that spiders cannot be identified without looking at the genitals, don’t believe them unless they’re talking about specific species instead of spiders in general. Nonetheless, it may not be known how to ID any species within whole families of spiders in your part of the world. This is true even for some families and genera in the US and Canada or Europe. (E.g. Dictynidae, so far as I can tell.)
I’ve read that before Peterson’s “A Field Guide to the Birds” was published in 1934, there was a similar subculture of bird taxonomists trained to identify museum specimens who insisted that it was impossible to identify birds without a specimen in hand. (And that some continued to insist this was true for some decades afterwards.) We’re in the pre-guide era of spider identification.