You Don’t Need an Interface for Everything

Ever seen an IMyService slapped on every class—even when there’s only one implementation? This video argues that most of those interfaces don’t earn their keep. Instead, lean on simple delegates or class overrides for dependency injection, and save interfaces for true abstraction points like plugin architectures or easily swappable providers.

Turns out this interface-everything habit stems from how .NET DI tutorials are taught: an I-first mindset baked into templates. The presenter walks through real examples of using delegates, overriding methods, and why sometimes a single concrete class plus a mocking library is all you really need.

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