> There are no conventions that write a date as mm.dd.yyyy
While slash is the most common, use of hyphens and dots as separators for US-style dates is not at all unheard of in the wild for manually formatted dates. The fact that it doesn't show up in lists of national “preferred formats” and doesn't tend to be commonly implemented as a prebaked format in software doesn't mean it's not a real thing people see and will interpret dates they see in light of.
While slash is the most common, use of hyphens and dots as separators for US-style dates is not at all unheard of in the wild for manually formatted dates. The fact that it doesn't show up in lists of national “preferred formats” and doesn't tend to be commonly implemented as a prebaked format in software doesn't mean it's not a real thing people see and will interpret dates they see in light of.