Well, if this is how “no sharding and no phasing” works, what is the guarantee that “no layering” will work not the same way?
Essentially, the sharding and phasing engine is still up and running in Classic, it is just that the zones in particular have been merged, so they are all on one shard. But, as you can see, it is not explicitly set to “merge everything” - but, instead, they set it to “merge Elwynn, Westfall, Redridge, Searing Gorge, Burning Steppes, etc” - and forgot about one zone, that wasn’t so obvious.
Which means, that the sharding engine is up and running, and even if everything seems turned off, it may suddenly fire up during the AQ event, because of server load.
If it isn’t really possible to explicitly set “sharding off” on a server, then we need to be sure that nothing unexpected happens in the moment of truth.