I've come full circle on Yext since I created this thread.
It is much more than just a citation tool and it makes perfect sense for a subset of my clients. At the same time, other services like Whitespark also make perfect sense. And guess what, typically using both services provides the best outcome. But it certainly depends upon what you're looking for and your client needs. But there is a marketing component to Yext beyond citations, so keep that in mind.
The reason why Yext does not delete duplicate listings is likely two-fold. First, those listings do not belong to Yext. They belong to the individual sites. Yext can express their opinion but it's up to the sites to determine what to do. But the bigger reason is that by deleting a duplicate, you are actually creating a scenario where the duplicate will re-appear at some point in the future.
Remember that duplicates are not just created because someone manually added a business. They are also created because the site has gathered data from any number of sources and it (erroneously) created a new listing. So if the listing is deleted, the next time that data is scraped you might find a new listing in its place.
So instead the duplicates are suppressed. They aren't deleted, but they will no longer show up in results. Also, just in case there were any links to the incorrect listing, a deleted listing would result in a 404 error. A suppressed listing has options like redirecting it to the proper listing.
Could Yext develop a way to permanently suppress these listings even if you cancel their service?
I don't think so because the listings aren't their's. The site could certainly change its algorithm so that if a duplicate is suppressed via Yext for more than x months than it is permanently suppressed. But that's up to the site.
You can certainly contact each of these sites individually and request that the duplicates be removed. I've done that. It's a huge pain. And it's why there are services out there that will remove duplicates for a pretty lofty fee.
I was one of those under the impression that Yext reversed everything when services are cancelled. But I've since learned that this isn't true.
The sites determine what to display based upon a myriad of factors. If a listing has been locked by Yext, that will take precedence over other sources that the site gets its data from. But when that lock is removed, the site no longer can rely on Yext for data pertaining to the listing, and it must once again look at all of the data out there and figure out what's best to display (again, I think this is another part of the value of Yext to have more control over what is actually part of data records). My assumption is that if a business has Yext for a decent period of time, that whatever data is included in the listings driven by Yext will likely propagate enough to have permanent influence even after Yext is cancelled. But again, that's up to the site.
In sum, Yext isn't evil. It's a great tool in the right situation. And fortunately we have other alternatives available in situations where Yext doesn't make sense or (as often is the case for me) when it makes sense to use multiple services.