I agree with mostly all his considerations. I only have a few notes.
Convergence it's not a profitable niche
Canonical did several attempts with convergence:
- Ubuntu for Android (2012) - Sadly, got no interest from OEMs. It was an interesting project, perhaps it came too early. It was almost ready for the market and we have better devices now. I hope to see it soon with Ubuntu GNOME :P
- Ubuntu Edge - Didn't get funded. ~$13m vs $32m goal
- Ubuntu Touch - I don't know how it was meant to be monetized, but we can say for sure that convergence is still a secondary/tertiary feature (only Lumia 950 and Galaxy S8 ship it).
I see Simon mentions a niche made by "all the hackers, tinkerers and people who were fed up with Google, Microsoft and the NSA snooping on them".
Canonical have been accused of spying on people through the Unity Dash or the Amazon web app multiple times. I don't think this was a viable option for them.
I believe convergence was the only way for them to hit the phone market. But reinventing the wheel using a custom stack didn't help in any way.
"Communication and marketing were rather chaotic and sometimes misleading."
Canonical promoted a lot their idea of a convergent phone. However:
The HDMI output needed for Convergence was missing on all official phones, and Miracast/Aethercast was not an equivalent solution.
I see the recent topics on this forum and all the answers we gave. I believe we're still running the misconceptions we've built during this time.
most people silently assumed to be able to run the same applications as on the desktop (Firefox, SIP clients etc.) and manage the phone with apt-get
That's surely one of the misconceptions.
Other reasons are the lack of apps and the need of more privacy.
I see we're all asking for Firefox and Libreoffice. I believe we only want a solution for these two unmet requests, and we took those apps as a symbol of productivity and privacy-awareness. The propaganda about convergence did the rest - after all Firefox and LO are the apps we run on our machines everyday.
"It wasn’t as open and community-driven as intended."
For me it's a thumb up. I've had/seen similar experiences.
"You left in mid-2016, long before the project was shut down. Why?"
I also left the core-apps dev team in the same period. It's the moment when Canonical shut down almost all the efforts on UT.
Lessons we need to learn: 1) we should not reinvent the wheel but use well-accepted technologies instead; 2) we need to address the real issues in the Ubuntu Touch OS :)
 And being saying that Ubuntu and Ubuntu Touch are the same OS