When I was involved in the used office furniture business, we used to junk these 'tank' desks back in the 1980s and 90s. If we happened to have a little spare floor space, we might try to display a couple of nicer ones and sell them dirt cheap. Nobody wanted them. The delivery crew hated them. I remember when the rubberized top surfaces got too chewed up, they used to make 'caps' for them--shallow boxes made with HPL to glue over the old tops. The 'side deck addition' is called a secretary 'L' desk They usually had a pedestal with a spring-loaded lift platform to put one of those weigh-a-ton typewriters on it.
Did we know there was someone out there who would want them? Sure. But we never managed to come up with a way to find that one in 10,000 customer and then put them and the desk together. Even if we did, we'd be lucky to get even $20 for one. So they got junked.