For one thing, I'm generally away from my computer when they call me, and all I have is my phone. If that isn't an issue, then port forwarding is an issue, or the desktop sharing they have on their computer is out of date, or they only have RDC, and I can't find a Windows computer. Sharing the desktop via chrome works pretty well, it still can be an exercise in frustration. For instance, my dad is a trader, and has 8 monitors. Getting him to share the correct screens takes forever. (I don't know how Windows decides where to open a window, but it seems like it tries to find a monitor my dad isn't looking at and opening it behind a window marked stay-on-top.)
I might use it if the problem was extremely urgent and extremely complicated, but I live about 30 minutes from them, so I'd just head over to their house if it was that bad. Screen sharing software was just one more thing to go wrong on their computers. This way, I don't have to worry about whether they have a version with a critical vulnerability, or if they'll fall for a social engineering attack and click on a teamviewer invite.
This software solves my concern about not being able to see what the hell my parents are doing when I'm telling them shell commands. This makes it really easy. They'd already be using Linux if I knew I'd always be able to use desktop sharing to look at their computer, and port forwarding/security/etc wasn't a concern, because connecting to a remote X server is incredibly easy. I already fix internet issues by SSHing in to the router (with key-based authentication) and then connecting to whatever piece of hardware needs to be tinkered with. I could probably do the same thing for an actual desktop, but I've fixed misbehaving servers via ssh on my phone before, and typing commands on a phone keyboard is an exercise in frustration.
In any case, I sat down with my dad and created a clean image of his desktop a while back. When he really messes something up he just reimages his computer. He likes the fact that I gave him the ability to bring his computer back from the dead himself. All his files are installed on a separate disk, which is constantly backed up, so he never loses more than about 20 minutes of work.
Easy as cake with TeamViewer
Then run the IPMI cable to OpenVPN on (eg) an RPi or even directly on the router.
You can configure and soak-test the router/RPi/etc locally, and IPMI is OOB.
Using an RPi/similar has some nice properties: you could VNC to that and then go from there to the IPMI console, and also recovery images stored directly on the RPi would upload quickly etc.
My chief concern with installing Linux was having to teach them how to communicate what is happening over the phone all over again. Outside of that, I'm pretty confident Linux is a good choice for my parents. My dad actually worked for Digital Electronics for years, and he's been interested in Linux for as long as I've been using it, but I think Linux would actually be better for my mom, because she literally doesn't care about her computer as long as it works. Her computer issues are generally the "the computer keeps telling me something and I want it to go away" type. Fixing those problems on the phone with Windows is a mess, but are basically trivial in Linux. My dad's issues are generally "I broke the internet," so this wouldn't be as helpful for him.
I'm really excited about this. I might honestly go buy an SSD to install Linux on my Mom's computer today. That way I could just drop it in her computer next time I'm at her house. My hope is that the boost in speed from Windows---> Linux, and the boost in speed from a 5400 rpm drive --> SSD would keep her happy long enough to get used to Linux. She's been complaining a lot about speed recently, and last time I was there I discovered she managed to her default user folder from the internal drive to an external USB backup drive. I have no idea how she did this, but it means she keeps running out of space because the backup process now backs up the backup drive recursively.