> somewhat ignored the fact that there were basically 0 apps on Symbian that anyone cared about in the slightest
That's not fully correct. Symbian was the leading smartphone operating system years 2000 - 2008 or so in Europe and some parts of Asia. Skype, browsers, games existed. I remember Skype offering me a refund when they discontinued the app.
I remember visiting software conferences in the US maybe 2005:ish and all the Americans had only feature phones. They seriously told me "All I want to do is call and text, I don't need anything else". The truth was that packet data coverage sucked in the US in those days.
These were Smartphones with keypad navigation (qwerty models also existed). They had packet data and the possibility to install apps, both native Symbian and Java (J2ME MIDP).
The problem was that developing for Symbian was too difficult for many programmers. Not only outside Nokia but also inside. I would claim that at least 40% of the Symbian developers did not fully understand how strings worked. Which had several types, none of which was called string and conversion between them or using the wrong one was a continuous source of bugs.
MIDP was too limited in its sandbox to build truly competitive apps.
When the iPhone came and capacitive touch started to win Nokia had nothing to offer. They had a couple of models with resisitive touch (requiring a pen or long nails), but all too little and too late.
When the Smartphone development started in the US Nokia was just obsolete. No competitive hardware and a difficult software platform. So Apple and Google conquered the world.