I probably have not worked enough with ASP.NET but I do not get that reference at all. In my experience deadlocks in databases are rare and do not happen on simple databases.
Most asp.net workshops rely on SQL Server, which up to version from 2012 did not support MVCC and relied on locking on writes and reads. The problem is, it had problems with web-kind load. If something was writing into a table X, and there would be a parallel query for table X join... (especially including index seek and not just lookups), you'd get into territory of heavy locking. Add ORM to that, which wouldn't let you influence the order of the joined tables and you've just got yourself a deadlock. This happened on a few occasions in a few different projects I've worked on. The real problem is: there is lot of technicalities you need to know and understand, to use it. Some NoSQL solutions (including MongoDb) try to abstract away those technicalities, and that was the point of my comment.