Less ram than my phone (Nexus 6p), than my TV player (Nvidia Android Shield), than any device I use? Is that a high amount?
Of course, you can serve static html with way less ram, but the shitload of features of Discourse has to be somewhere. And that is webservices(normal and long polling) , redis, postgresql, nginx, and some gnu/Linux binaries (image Magick, tar, and cia). Not counting an architecture where you can write a enterprise grade plugin in hours.
If the goal of the project was to run with the smallest ram possible, OK. But this isn’t the goal. The goal is a modern forum that runs on modern hardware.