I had the exact same idea a while back as well. Jotted down some rough notes, came up with a name for it, ran it past a couple of journalist friends. It has merit but it's the usual chicken and egg problem.
Perhaps come up with something niche or location specific (or white labelled so it could be run out as niche/location oriented by someone else) and try a focused launch.
Another option, and this would be easier if you started min-viable-product-style with a few niches, is if you listed some "experts" then ran it past them (explain the idea and that you've added them, but can remove them if they like - make it very personal rather than spammy) and then pitch it to journalists and bloggers once there are some experts listed.