It should be a bit concerning how uncompetitive the market is that you really cannot even try to launch a mobile OS of your own as a product, since you are beholden to telecom operators and handset manufacturers on both ends, all of whom have government granted monopolies or protection in their own industries to prevent competition.
Take Microsoft - it became a handset manufacturer and is still struggling to make Windows Phone a winner.
That was because Microsoft could have all the money in the world, but couldn't operate a cell network out of thin air that would promote their devices. They also had limited access to hardware - they had to outright buy Nokia to even get minor device manufacturer access, and even then few companies ever offered Windows Phone devices despite Microsoft throwing hundreds of millions of dollars at it.
When Microsoft cannot make inroads - a company that outright buys entire business sectors to own competition - its disastrous.
And the implication from that is that if vendors aren't looking to make a ubuntu phone, it's because their customers aren't asking for a ubuntu phone. Regardless of how many layers there are between Canonical and the end user, there weren't a lot of end-users asking for a Ubuntu phone.
If you make a mobile operating system but you don't make devices, you need to be able to convince device vendors to sell the product for you to end users. They didn't succeed in that.