Acrobat Customization Wizard DC - Default viewer for PDF files - What does this mean? --> On Windows 10 this option will only set default PDF viewer for browsing and file preview

When using the Acrobat Customization Wizard DC to build the MST for both Reader and Acrobat Pro, what does this mean under Default viewer for PDF Files --> "On Windows 10 this option will only set default PDF viewer for browsing and file preview." I cannot find anything online to explain this not even in Adobe Support. I chose the SDK forum since there isn't a selection for the Customization Wizard. I would hope you all know the Customization Wizard for working on Reader and Pro. Thank you.