That's a cynical take -- I'm not sure it's untrue, but another factor is cost. Things that are not meant to be maintainable also tend to be cheaper to design and build initially. You don't have to worry about maintenance access when you design the product, or making the components replaceable, or using industry-standard parts.
By avoiding maintenance concerns in design and production, you can sell a cheaper product, and the vast majority of buyers will look at purchase price and not total cost of ownership when they are evaluating choices.
Additionally, production is more easy to automate than repairwork, and what you cannot automate you can outsource to countries with cheaper labour.
As long as demand (and other circumstances, i.e. currently somewhat of a "Ha!") are sort of predictable, hiding the length of your supply chain can be easily done by shipping things over in bulk and sufficiently in advance. People won't care whether their widget was produced five minutes ago in the back room of the store or three months ago on the other side of the globe and then shipped over on a slow boat, as long as it's available when they want to buy it.
For repairwork on the other hand, the same procedure doesn't work out as well, because you can no longer hide the latency inherent in minimising shipping costs.
I'd say semi deliberate. Market dynamics evolved to cut prices extremely low.. so manufacturers don't make enough cash to want to design complex and manage parts etc.
Most printers are horrible.. even the assembly is hell, but if you pay a pro model (6x times the price) you get a modular and easy to open device.
