Do Data Warehouse standards allow foreign key constraints at a dimensional model?

Performance!  Data Warehouses ingest millions of rows everyday.  And having constraints like Primary Key / Foreign Key is a real killer. It hurts the load performance and also causes hectic maintenance, to constantly monitor and respond to failures. Its good and bad though)

Remember, all the modern data warehouse platforms (Snowflake / Bigquery), do not even have an option to create constrains / enforce them on the tables