No, a mature company like Boeing will have parts for planes stock up for decades even the model is no longer produced.
Seriously? You're comparing 3DR (a retail manufacturer) to Boeing (a major commercial and military aircraft manufacturer that when they have a good or bad year it there's a line item in the US GDP that you can point to and say - "yeah, that blip there is Boeing.")
So as an FYI I live in the heart of Boeing country. I know Boeing employees in manufacturing, engineering, and support. My wife is a Boeing engineer and my brother-in-law is in Boeing manufacturing.
I drive past the Boeing spares warehouse frequently (side note - it covers 15 acres and won an award for having the flattest concrete pour in the world when it was built.) They have spare parts from an entire wing down to something so small you need a magnifying glass to see it. They don't have decades of wings in that building or any of their other spares distribution centers around the world (there's 7 of them). Yeah, they have lots of spare parts but to warehouse decades of parts is a waste of money.
For out of production aircraft they have a build center in Long Beach, CA where they fulfill requests by machining them.
Just because 3DR isn't selling parts directly to the end user doesn't mean that they're not manufacturing and making them available as is evident by the parts available at
B&H.
3DR is in the retail market where margins are razor thin and you need to keep costs under control. If you were a retail manufacturer. Which would you rather do?
A) Make 1,000 motor pods, ship them to your warehouse where you store them until an order is placed for 1 of them, then pay people to take the order, pick and ship the pod.
B) Make 1,000 motor pods, ship them to B&H and let them deal with the end users.
The cost may be a wash but the uncertain intangibles of the infrastructure required to support such an operation are shifted to another company, thus reducing your uncertain expenditures and allowing for better budgeting and forecasting.
When you're a young company you're not going to get B&H to even talk to you. When you've matured a little you can get retail aggregators to move your product for you.