Hi and thanks for your blog post. I must say I was skeptical at first as I had already tried deltachat and I wasn't convinced. At the time I was under the impression that the main advantage of deltachat over other IM services was that there was no need for creating another account. I just used existing email accounts and then hit (as expected) the issues mentioned in your post among others.
It's a shame because I think that was the one thing that could have made DeltaChat worth the try for non technical user.
I can see myself use it, as a concerned, motivated "technically educated" user but it seems it's not mature enough for ordinary people, as I read some features are missing regarding user-friendliness and a lot of people in my contacts list would just dismiss it if it doesn't show the same level of features as what they're currently using.
In the meantime the best middle ground I found was matrix with a select list of bridges but I'm not losing hope of finding some better alternative so I'll definitely keep an eye on DeltaChat.