We all know the importance of citing sources in genealogy. It is absolutely a necessary practice in any form of research. Why then do so many published genealogies lack citations?
Citations are important for several reasons. First, when publishing your research, you need to convince others that you applied a sufficient level of due diligence to ensure the correctness of your work. For example, many of us have looked for people in the IGI, and so we all know how unreliable it can be. But think about it: Each entry in the IGI is based on the work of a genealogist. If you see a published genealogy without citations, you really have no idea about its quality.
Second, citations can help you in your own work. When I started genealogy 22 years ago, many programs didn't have any meaningful support for citations. We had to use notes for that, if we cited our data at all. So when I resumed my interest in genealogy a year ago, I had to spend some time to line up all my data with my sources, mostly hand-written notes in a number of three-ring binders. I was able to find a source for everything, except for a few things. I ended up deleting some people since I had no record of how I got their data.
When you know where your information came from, you have a good idea about its quality. If you get some data from a published source with no citations, you can flag that with a confidence of "Low". Or perhaps "Very Low". You can then use that information as a starting point in locating sources with a higher confidence level, such as the original civil or church records.
Version 5.5 of the GEDCOM standard has been in force since 1995, and so all genealogy software now should have a reasonable level of support for sources and citations. Unfortunately, not all do. For example, when evaluating WikiTree, I was disappointed in how the data was presented after importing some sample data. While it does a reasonable job with citations on import, WikiTree requires you to manually edit the raw GEDCOM data into a presentable form. For any new data, you need to manually edit the text, including the citations. Clearly, in my opinion, WikiTree is unsuitable both for serious research and for publishing data. However, note that point VIII of the WikiTree Honor Code is "We cite sources". When I considered joining WikiTree, I took that point to heart, and spent considerable time making sure all my facts were properly cited. Time well spent, though. It had to be done.
I use the program Gramps, which does have good support for citations. Now, I never add any information to my database without also adding a citation. Here's a useful tip when using Gramps: Always keep a clipboard window open. Since one citation can support multiple facts, when you create a new citation, drag and drop it right away to the clipboard window. Then when you need that citation to support another fact, you can drag and drop from the clipboard to the new fact.
Here's another Gramps tip: You can create a custom event filter to find events without citations. Set the name to 'Events with <count> sources' and values to 'Number of instances:="0"'. This way you can easily find uncited events.
These days, there's really no excuse not to include good citations. Considering that you can now easily download images of original source records, you can even include those images in your citations. Even if you still read microfilms at your local LDS Family History Center, you can often digitize images from the microfilms. Sure, a single image may take up a lot of disk storage. But disk drives are cheap, with external drives costing roughly $100 per terabyte. How much can you store in 1TB? About half a million images from FamilySearch.
So get to it! Cite those sources!