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The facebook post is kind of goofy. Definitely not written by someone that took any advanced biology.
The problem with this virus is indeed it's newness but it has nothing to do with the fact that it's a RNA virus. Many other viruses we get are RNA viruses and we can deal with them just fine (ex: the common cold) others not so much (ex: measles, ebola). DNA viruses are no slouches either (ex: smallpox, herpes). And retroviruses are nasty too (Ex: HIV).
This has to do with it being new so nobody's immune system has previously developed immunity and the fact that's it's incredibly good at spreading - so the whole population is getting it at the same time and taxing the health care systems. All this combined with the fact that in some people, the immune system is not able to build the immunity required to fight it, develop severe pneumonia and cannot recover. In the end, it's the sheer magnitude of people that will get this.
(Full disclosure: I have a PhD in molecular biology though I've been away from the lab bench for 10 years and now work in I.P. related to biotech- I'm not an expert in virology or epidemiology but deal with things like PCR tests, sequencing and diagnostics all the time)