I've never heard of arachnophobia being a fear of webs rather than, you know, the actual arachnids. It's utterly bizarre to me that that would be GP's first thought...

Where there's a web, there's gotta be a spider?

Right, but even if that was how phobias work, which to my understanding it's not, it still depends on being afraid of the spider to be afraid of the web, while the poster above is implying there are some people who are primarily/only afraid of the web.

So when I googled it while in the middle of writing my last comment It was heavily implied that there was not a separate phobia for just the web. https://www.healthline.com/health/mental-health/fear-of-spid...