That's not exactly true. Nokia pretty much owned the featurephone market and had all the right relationships with telcos that were the primary channel.
The excuse they were too large and bureaucratic to change does not fly when you are the CEO - he had the power to make the required changes. Nokia also had good technology, on par with Android, at least. The mistake was not to realize that iOS's and Android's strength is not on their technology, but the rich ecosystem built around it.
CEOs have less power to steer the ship than you think. The main assets of a corporation in a knowledge industry are the particular skillsets of its employees and the web of personal relationships between them. If the knowledge required to adapt to a market shift doesn't exist within the company, then the only option that a CEO has is to bring it inside the company, and assimilate it into the existing web of relationships without having the existing power structures reject the new talent. This is challenging in the best of times, with the most forceful CEO, and virtually impossible when you've got only a couple years to live, a complacent workforce, and a board that's only interested in salvaging what they can.
Assuming that you're right that iOS and Android's strength is their ecosystem rather than their technology, there's no way Nokia could've capitalized on that. They couldn't bring on hardware partners, like Android, because all of the hardware partners were their competitors and wouldn't trust anything they did. They had no expertise in engaging independent developers; Nokia has never had a product where they've had to, and their OS (Symbian) was reportedly a pain in the ass to develop for. And while they knew how to build a mass-market consumer product, they didn't know how to build a mass market consumer platform - first-hand experience of what consumers could do with an open-ended computational device wasn't in their DNA the way it is in Apple & Google's.
CEOs cannot make magic, but Nokia had everything they needed inside the company except perhaps the willingness to realize the market had changed and that they had no longer a viable application layer. That much was evident since the first Android - it would be a two horse race and Android was the only one they could ride.
Except they weren't so strong on software and platforms. Their programmers had mostly worked on feature phones, and Symbian was made by an external company at the time.
The first reaction to the iPhone was to buy Symbian in 2008, which in retrospect is so wrong that's surprising, but the vast majority of people at all level (people in the street, geeks, executives) didn't understand the real change that iPhone was bringing until maybe 2009-2010.
Then Nokia tried to fix the software problem buying Qt. That ended up as being a mistake as well. Qt was built on the idea that you can create a UI framework that unifies all platforms; that was realistic when the support OS were all desktop and thus similar in main concepts and interaction patterns; Qt also nominally ran on embedded at the time, but the experience was suboptimal at best. So Nokia drank the idea that adding "another backend" to Qt was the solution, also because developers loved Qt. But of course it's not that easy. It took them 2-3 years to come up with a new codebase that could handle the new interaction patterns (QML) and that's a geological era in smartphones. At that point, they still didn't have a complete working solution for a qt iPhone killer, and Elop had to cut the chord. That day, the fate of Nokia was already written.
Once upon a time there was the presentation of the first Maemo device to the employees. The feedback about it becoming an hit if GSM support was added, was just ignored.
Very few also had the opportunity to see a Nokia 7710 live besides us, as it was quickly killed after a few months on sale.
Also the famous blog post about how shitty Symbian C++ was, that only Nokia employees would be willing to use it.
Some years ago The Register had a pretty good report about the internal politics going on there.
The excuse they were too large and bureaucratic to change does not fly when you are the CEO - he had the power to make the required changes. Nokia also had good technology, on par with Android, at least. The mistake was not to realize that iOS's and Android's strength is not on their technology, but the rich ecosystem built around it.