I felt like that guy had some reasonable complaints. But in general complaining that you have to setup and configure web server like this.. I don't know. Yes, having a neat docker fast setup is convenient, but you do need a bit of skill at setting stuff up to run a server I think. So, perhaps if he doesn't want to do some sysadmin work maybe a new beta level piece of software isn't the best choice and did the right thing by no longer running an instance.
kbin is overall IMO fine, it has a learning curve and is a bit new. Currently most federation issues are resolved or resolvable. To be fair some of them were caused by issues with lemmy (since fixed, but not taken up by all instances) and (cough) a certain lemmy instance in particular blocking kbin in general. This kind of thing is going to make unavoidable federation issues. When I couldn't connect to lemmy instances properly my messenger processes were restarting all the time. Now? Not "crashing" nearly as much. By crashing, it's just that when a critical level error happens the process stops, and is reloaded right away. It doesn't mean they stop and messages are no longer processed.
Having said that the backend and especially server admin panel need work, a lot of work. But, these things are being worked on all the time.