pianomano8: This needs to be highlighted in some way. I had /NO CLUE/ Myst was a ScummVM game.. I don't associate the two at all! As a Linux user, I've been trying for years for Wine to support Myst, and for the past few years if I'd just known to try ScummVM I'd have been all set!
Please GoG, also consider packaging Myst: Masterpiece Edition with Scummvm for Linux. I'm not sure if your license will allow, but DANG. Apparently Riven is supported too.
I'm pretty sure that it was very recently that the ScummVM project have had success in getting the Myst games to work reliably with ScummVM. From my understanding, they don't change the games, they simply change ScummVM to make the games work. In general, many games were not based on ScummVM initially. Instead, the ScummVM project continuously add other games to support with their software. Riven is another that was recently added that did not ever use ScummVM. So, no, I don't think you have missed out all these years, it wasn't an option all that time.
I think in general, you can simply copy all the games from the various copies of ScummVM and put them into a single instance of ScummVM. That can save disk space, and ScummVM then becomes a sort of game manager from which you start and then choose which game to play from a list. I've done that with a few games and it's worked so far.
That also means you can update to a later version of ScummVM when it fixes any issues it had with some of the games. The game stays the same, but ScummVM is what changes. So copy it out of an old version of ScummVM into a later version of ScummVM.
While ScummVM is intended to be cross platform, sometimes the same game might have different issues on different operating systems. The ScummVM website lists the level of success they've had in trying to get each game to work, sometimes with notes of differences for operating systems, along with their plans for other games. You might as well as try your games on different operating systems, as it's simply ScummVM that has to work with the operating system. The "VM" is for virtual machine, after all.