In the past days, a new Wikipedia contributor edited Wikipedia and made a great contribution, except... This user added zero sources, and the article in what the edit was made was about a living person. So the verifiability is a problem and in conflict with the policy Biographies of living persons. This was just one example of thousands that have to be dealt with every day in Wikimedia. And every day the community tries to maintain the quality of Wikipedia and has to deal with this kind of edits.
I asked myself the question: why did this new contributor not add any sources?
I logged out, went to an article and clicked edit. Made some modifications (in the Visual Editor), and then clicked Publish changes. In the steps I took to edit the article, I got nowhere a message that Wikipedia wants to have sources for the information I added. Nowhere!
I hope that every experienced user by now understands the importance of adding sources. But we cannot expect from new contributors to already know this. They need to be informed that adding sources is needed. They do not go first read the manual of Wikipedia with all the help and project pages, they just start editing right away. They think, link in many other platforms, that if they do something wrong, they get a message while editing/uploading/etc.
For some strange reason, if you edit Wikipedia, you get no notification at all that you need to add sources, even while this is one of the most important pillars of Wikipedia. The result is that a lot of work of these new contributors gets lost, because the information is removed from the articles because of a lack of sources. If those new users would have got a message in the Visual Editor during the editing, a lot more contributions would be able to stay in Wikipedia, less new contributors would get demotivated, and it would reduce the workload of existing users who do the maintenance every day.
As with the influx of edits without sources nothing is done, the Dutch expression "mopping with the tap open" (Dutch: dweilen met de kraan open) applies here.
Romaine