If you're willing to search around on Ebay/AliExpress, you usually can get individual parts: either gray market from a service centre, 2nd shift or overruns. The big exception's for Apple parts.
Contrast with Sears: Here's 250+ parts available for each fridge they distribute, shipped to you direct, with manuals:
I bought repair parts for my parents' 20 year old garage door opener from them. PSA: open it up and grease the nylon gears every decade so they don't turn into a snowmaker.
The other thing is making a small-run weird and pricey car and then mostly ditching it as a supported product. Putting aside any value judgements about the practice of making and selling products in either of those ways, I still don't see any 'philosophical' connection to Apple or really, you know, anyone else not-making bespoke custom products.
"A lot of early adopters were probably worried that Tesla would go out of business and they wouldn't be able to get parts. Tesla is still in business and there still aren't parts."
I guess that could be interpreted as though Tesla would eventually support the early models, but it's clear that they're not providing parts for any model in small or large production.
The comment you quoted says that buyers were concerned about parts from the get go, presumably as most buyers of nigh-bespoke custom sports cars are and as most buyers of anything Apple makes aren't.