Every AEO and GEO tool on the market is built around your domain. Point it at your site, and it will tell you whether ChatGPT, Perplexity or AI Overviews quote your homepage, your blog, your docs. That is a real question and those tools answer it well.
It is also, increasingly, the smaller half of the question. When somebody asks an assistant whether your product is any good, the answer is frequently assembled from places you do not own: a Reddit thread, a review listing, a YouTube walkthrough, a post one of your customers wrote on LinkedIn.
On-site tools cannot see that content. Not because they are badly built, but because it lives outside the domain they are pointed at.
Why this gap exists
The category grew out of SEO, and SEO has always been organised around a property you control. Crawl the site, audit the pages, fix the structure. Off-site content breaks that model on the first step: there is no site to crawl, because the content is spread across a dozen platforms and none of them are yours.
- You did not publish it, so it is not in your CMS.
- You cannot edit it, so the usual optimisation loop does not apply.
- You often do not know it exists until someone forwards you a link.
What to do about it
The first move is not optimisation, it is visibility. Before you can argue that a community programme or a creator partnership is working, you need to know which specific pieces are being quoted, by which engine, in response to which question. Until then the conversation stays stuck on impressions and vibes.
That is the gap Plug is built for. Not a replacement for your on-site tooling, which is answering its own question perfectly well, but the other half of the same picture.