Q: If I used a database and there is no DOI, why can't I just include the database
information all the time?
A: Try to get your readers to the material in a universally accessible, simple, and
direct way. Many databases are subscription based or university specific and thus
not accessible to everyone. Their content can also change over time. Although
publisher homepages may also change (which is why DOIs are preferred), they
are accessible to everyone and easy to find online.