Consolidating the useful and relevant bits of the discussion into a cohesive reply.
Having periods in a filename beyond separating a filename from the file extension can cause a wide range of issues, particularly when files are moved between platforms and operating systems. It's similar to other special characters in filenames, such as spaces, when documents are placed online. This has been the case for more than 30 years. As a result, a worldwide standard workaround developed. It uses underscores to replace potentially problematic characters such as periods and spaces.
PDFs, being documents that are frequently transmitted between different operating systems and posted on the Web need to be safe for all operating systems and the Web, and thus must use platform-agnostic file naming conventions.
In the past, users had to manually make the filenames safe. Adobe Acrobat Pro DC automatically replaces periods in filenames with underscores to prevent that additional manual task. While this does create inconvenience for some users who prefer the periods, it removes inconvenience and numerous technical issues and incompatibilities for the majority of users, computer-savvy and otherwise.
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