Is this extreme planned obsolescence?

Probably. HP is in textbooks as an example of market segmentation:

HP had 2 models of a printer, an office and home version. They were identical, but since offices spent more on printers, the office version sold for a higher price.

Sales reported lost office sales due to potential customers noticing the numbers for the office and home models were identical.

The solution was to add an extra chip to the home models to slow down how quickly they could print. This increased manufacturing costs.

HP made the home model more expensive to manufacture (.: less profitable) for the purpose of making them worse so another market segment would be convinced to pay even more.

Gosh, why are their printers so bad to control?

A lot of HP's user-hostile/bad design isn't planned obsolesce but the efforts and effects of locking users into a walled garden.

Printers that are cheaper than a full ink cartrige and pushing registering/more HP services hard put users into a position where they're willing to put up with a lot before they go out and spend hundreds on a non-HP printer.

That enables HP to spend less on the product being good without losing customers.

btw Anyone have a recommendation for a printer brand with less painful software?