I understand your complaints. However, despite deprecation, I can use Triple DES as a choice for the DEK. It's valid on a SQL Server 2016 instance. There's nothing in the question about compatibility level for the database. A database on a SQL Server 2016 instance is not required to be on any particular level.
I'm not sure I think that I need to specify the compatibility level for every database as well, but maybe that's the case. I would say that you're making a leap about what options are valid on SQL 2016 and extending that to assume the database is always at the level of the instance.