Nokia? Lack of scale?

Nokia couldn't compete because they made a string of incredibly poor investment and management decisions, such as the N-Gage, until their mobile division was eventually bought out by Microsoft. Even with Microsoft's scale they couldn't turn things around.

The reality is that there were a number of mobile phone manufacturers making lots of really bad decisions whilst trying unsuccessfully to compete with the likes of Apple and Samsung. They aren't gone from the market because they lacked scale: they're gone because they were stupid.