David - the Title of this posting was made more as a Joke. As nobody who knows how Obsessed I am with 3D Printing - could possibly take this posting Subject line as serious - just sayin'...
Now, to contradict one of your points. In fact, the core of the business behind the machines sold by VisionMiner is to actually produce USEABLE Parts. Yes - generally printed in more exotic materials like PEEK & ULTEM & Composite versions of those materials.
Even CF Nylon parts have their usage - as Viable parts. Now, I WISH I could share a pic of the particular part - but, the printing of these particular parts at VM is very much under NDA. I will only say - they nicknamed them as "Piano Parts" - because they way they look. I will say - they are big parts - like maybe 12"x18" each, they are used in Pairs, and they charged the co.s a Pretty Penny for them. I don't remember their selling price - but, it's in realm of like maybe $250-450 a pair. And, the co. gets them in large sets - I think last batch I worked on was like 10 pairs! The last detail - it's used for Drilling rigs - not sure if it's Oil or Water - but, I think maybe it's for oil drilling.
So - YES Indeed - there are polymer FDM printing or parts that are Very, VERY Useable items. Also, although not generally FDM - co's like Shapeways have been printing things for customers for YEARS now - and I bet at least 75% of the customer printed parts are useable items and many probably STILL in use!
-K