The dawn reference also has an open issue for adding this support to the theme https://github.com/Shopify/dawn/issues/333
@Shoplogy , @Laurie_ONeill , @jmp , @mattnz @LetsGetDigital
To clarify the tag system is still very much a part of the shopify platform, it’s only there is no UI and UX to support that in the DAWN theme.
The dawn theme is free and not your only choice.
There are also others themes still available that come with UI’s for tag-based collection filter bars or filter sidebars.
There are plenty of tutorials, code samples, experts and apps that can aid in customizing ANY theme that lacks feature-X to have that feature.
You are not limited here at a platform level but you have to pick and choose your tools and investments.
This is why you evaluate a theme before over extending and finding it out it lacks feature-X.
If your business model has a complex information architecture and needs a complicated navigation system invest in getting that tool or make sure the primary tool(theme) comes with it, this is a key differentiator of successful merchants.