I was under the impression that this is effectively teaching people to speak without any accent at all

>effectively teaching people to speak without any accent at all

There's no such thing as "no accent"

I used to speak with pretty close to no accent as I learned English in Okinawa, then went to 2nd and third grade in Arkansas and then went to school in southern Virginia. The mix resulted in an unaccented speech compared to most localities. Now I have a slight southern accent.

In English at least. Some (maybe most? - no idea honestly) languages do have more or less official standard accents. For German, that standard accent is very close to how people speak in Hannover.

Oh no... it's an "accent". It's just a "desirable" one. Kind of like a posh accent in England.

Well no, definitely not - it’s just meant to be as clear as possible. The point is to make sure as many people as possible can understand you, which is very important in informational and entertaining broadcasts.