This is an infuriating topic to read about because everybody seems to be varying levels of uninformed.
I worked at Nokia's R&D facility in Ruoholahti briefly in 2011, so I got inducted into the inner sanctum of history regarding the phones.
Symbian was designed for very anemic hardware, there were very tight constraints it's a marvel that the thing ran on what it did. The iPhones first CPU was at least an order of magnitude (and then double it again) more powerful than what Symbian was designed on.
the iPhone, famously did not meet any of the internal tests at Nokia, no drop test, battery life tests nor usability tests for blind people passed at all.
Basically from all avenues it looked dead on arrival.
However, it was obviously _not_ dead on arrival, and so Nokia started looking at things from a "UX first" perspective, the engineering culture was still around though, so, not a major "product" team or graphics design team to be found on the floors of the R&D facility.
But they started this effort _after_ the iPhone had launched, and these projects take a long time.
That's what Maemo was. And it was later merged with Intels efforts and named MeeGo. And everyone who used that system seemed to really enjoy it.
It was, indeed, killed in its crib by Elop. Although to be truly fair, the iPhone and Android were very incumbent at that point.
Symbian was considered obsolete or deprecated internally, not for lack of very intelligent design, but because people seemed to care for things other than that Nokia had believed people cared for.