I see two general topics:

1. Should we use third-party libraries in the Core?
2. Should we consider AngleSharp for parsing?

Third-Part Libraries

HTML Renderer is currently very lightweight and has no dependencies. This has always been proudly presented as a feature of the library.

With .NET the "batteries included" era is changing, as certain "built-in" / .NET features are only available through NuGet packages (e.g. System.Text.Json).
Are those libraries also considered "third-party"?

If we end up having to potentially specific certain package references anyways, what's speaking against third-party dependencies?

AngleSharp

There's quite a bit of research & knowledge that went into the HTML & CSS parsers. At the time, this was certainly also quite unique.

On the other hand, the parsers are quite brittle, the implementation is not very flexible and there are still many unsupported syntax elements. Additional, the original maintainer and knowledge holder is no longer maintaining HTML Renderer and thus can't be relied upon.

Wouldn't it make sense to replace these parsers with AngleSharp?

The main thing I struggle with is, that I don't really like accidentally build monopolies, i.e. where only one implementation exists in the world.

Please provide your views and thoughts on that matter! 🙂