MicrosoftI can see there are some benefits of hosting simple html files in SharePoint but I am unsure, when I should recommend this features to my customers compared to the other existing features. Usually using normal pages for normal content offers more features, like using WebParts for dynamic content. More advanced use cases are not possible because of blocked external API calls and local store.
So the only remaining option from perspective would be to use html pages if you have generated, static html content and want to use SharePoint for hosting.
For more advanced (pro code) use cases SPFx for SharePoint Online and Add-Ins for SharePoint Server are still the way to go (on SharePoint Server SPFx are currently not a good alternative, because the supported React version is way to old and the extension options very limited).
In this case the good old app parts of the Add-Ins are very similar and even better because they offered an option to host html as iframes on a SharePoint page but with the possibility of whitelisted SharePoint and external API calls and local storage access😀
