https://twitter.com/vesselofspirit/status/123748864242514739...
According to the song lyric, "novel coronavirus / has a lipid outer shell". So it seems like some viruses have taken advantage of this.
Anyway, I think the important thing that the other commenter was saying is that mRNA needs to be carefully packaged to be medically useful. You can't inject pure RNA as a vaccine because not only is the mRNA going to be quickly degraded before it gets anywhere but if the immune system sees any RNA floating around by then it kicks itself into a frenzy because free-floating RNA is usually a sign that something nasty is afoot.
The envelopes used in an RNA vaccine are generally simpler, because they're working under different constraints than viruses. For example, their envelopes don't need to be easily manufactured in a cell.
But some RNA and DNA vaccines do use viruses as their delivery mechanisms, eg the J&J COVID vaccine.
Moderna vaccine has to be kept in -70 C. Viruses that can survive for any extended period of time only in -70 C won't find many hosts.
Also maybe the process of creating virus shell can't naturally be done without protein scaffold.