Unsolicited opinion: If #Mastodon wants to be a part of the #Fediverse that encourages small #selfhosted instances to be part of the whole, then it has to be a lean system able to be installed on second-hand/hand-me-down hardware and it should run reasonably well.
ElasticSearch/Java is a barrier to that. It is a huge memory hog compared to the rest of the system.
#footiMac #Debian
IRC, or XMPP at worst, should be the gold standard to follow here. Those things can be installed on Pentium IVs that you can get from rural school trash yards, and still run reasonably well.