Dropped
It has finally gone fully "under the hood": I no longer work with ADO.NET directly — EF Core and Dapper cover everything. Understanding what happens inside still saves me during debugging, but as a day-to-day tool I'm putting it away.
Using
ADO.NET is the foundational data access tool in .NET. Before Dapper and EF, it was the only way to talk to a database: open a connection, write a query, read a DataReader or fill a DataSet. Clunky, but it gives you full control. Understanding ADO.NET really helps later, when you're trying to figure out what any ORM is doing under the hood.