Just for information, I generally agree with what you said here, except in
this particular case rsyslog is not a generic data bus, and Fluentd and
logstash are, so they're useful on their own merit. They're just often used as
merely log transports, which overlaps with rsyslog.
If you don't need to curl|sh from a .io (or .sh) domain to install it, it's not worth using apparently.