Did you try to develop for Symbian and push anything to their store? The experience was so terrible, that it was easier to build for a jailbroken iPhone, pre-appstore, than for Nokia. Nokia App Store - that was introduced a year after iPhone's App Store -
https://www.datamation.com/mobile/nokia-unveils-online-app-s... . As for a user friendly GUI - you must be kidding here.
Before iPhone, devs had to ship apps through web, or strike deals with mobile operators - which were crazily terrible - I remember a story of one operator who had a deal where they literally took all the money, and it was up to a developer to figure out their business model.
As for Elop bringing in Windows Phone 7: my understanding was always that this was literally the reason he was brought over to Nokia -- because they were in such a deep hole. He was brought 3 years after the iPhone, when Nokia/Symbian was already on a downhill slope.
At that time it was reported as a potentially saving move for both MS and Nokia, because their platforms were struggling - https://www.informationweek.com/it-leadership/nokia-to-embra... -- "In July, Nokia reported a 40% slump in second quarter profits, as it has struggled to maintain its lead in the booming smartphone market.
Mr Kallasvuo has been facing increasing pressure to quit this year after Nokia issued two profits warnings and its share price fell by more than 40% between March and June."
As for the lack of vision though, I agree. And that is what's happening with Google right now. They are introducing AI chaotically left and right, and there is no serious vision behind it all. I expect Apple will show how it should be done, once again - but I may stand corrected after Monday's WWDC :)