Development release? Currently I'm on 16.04, and I've never been on a development release of anything on Ubuntu. I'm just describing the behavior I usually see in practice (which it seems someone attributed to "D-BUS" [1]). Obviously the logon session doesn't get messed up if all I'm updating is something irrelevant like Firefox, but if I update stuff that would actually affect system components then there's a good chance I'll have to reboot after the update or I'll start seeing weird behavior. This has generally been my experience ever since... any Ubuntu version, really. It's almost ironic that the most robust thing to update in practice is the OS kernel.
All I can say is that, based on everything I know, that's not the current experience of the majority of users, so it doesn't seem fair for you to generalize this to some architectural problem. I don't know if you unknowingly have some edge case setup or what.
Are you reading the same comments I'm writing? I was literally point-by-point saying the opposite of what you seem to have read me writing:
> You: All I can say is that, based on everything I know, that's not the current experience of the majority of users
>> Me: Yet from everyone's comments here I'm guessing I must be the only one who encounters this.
???
> You: It doesn't seem fair for you to generalize this to some architectural problem.
>> Me: I don't get why it happens in every instance, and there might be lots of different reasons in different instances. IPC mismatch is my best guess for a significant fraction of the incidents.
I have been running Ubuntu since 2004, and except for Firefox which tends to destabilize on update, I’ve observed this twice in 14 years; I update weekly or more often, and reboot every few months (usually on a kernel update I want to take hold)
Maybe it's because you update often so there are fewer changes in between? I update far less frequently.. it's not my primary OS so it's not like I'm even on it every day (or week). I use it whenever I need to.
Have you filed any bug report or point to one? All i have seen is a lot of handwaving about "IPC mismatch", things will not fix itself unless people actively report/help fix issues.
[1] https://news.ycombinator.com/item?id=16257060