The real problem with the older MacBooks (Pro) is weight really, for a machine that I have to carry with me every day.
As far as I know, there aren't that many 13 inch or less light options with more RAM outside of Apple either.
In comparison the MBP 2012 and a MBP 2016 do not differ in weight so much (1.4kg vs 2kg which is basically a package of flour) and if I am honest I don't really recognize the difference when carrying them in my backpack.
But it depends on the bag as well, because if you use a messenger bag for example the strain on the shoulder and the back is probably noticeable. Also many people like to carry their notebooks around with one arm / hand and of course this will be a huge difference then.
Some people like to use the Thinkpad X1 or the Dell XPS as a replacement but I don't have any hands-on experience with those.
I hope someone will recognize the gap in the market and jump in to produce 13 inch, retina screen uni-body metal notebooks with the ability to upgrade the parts and with all the ports you still need when not living in some bubble where magically everything was converted into USB-C overnight.
Of course 16GB is the max. you can put into an MBP 2012.
But: Who needs that anyway? Yes if you do heavy tasks like 4k-stuff and 3d-rendering but for most tasks you do with computers it's quite sufficient.
Personally I move my tasks to servers if they need more resources.
For many people it's not even a case of "saving up for a machine," because they might be using donated hardware. For example the OLPC (One Laptop Per Child) project that runs Fedora on low powered machines[1].
Even for people who can save up for new machines and do install Linux on them, that $100 is still an additional expense they wouldn't have needed irrespective of any comparisons to Microsoft nor Apple "taxes".
For these people, particularly the first group, Electron simply isn't an option. So at best developers are depriving themselves of a future growth market but at worst they're excluding deprived sections of society who are already isolated from the IT industry as it is.
That all said, I don't mean any of this as a criticism of yourself nor what you had written. None of what you said it technically nor morally wrong despite the points I've made. I see this as similar to the discussions made about non-English speakers being disadvantaged when learning programming languages.
We're comparing to a Mac though, so that sentiment really has no place in the conversation. The cost of more RAM in the world of Apple is much, much more than $100.
I'm on the fence about Electron. While I do love how it's made portability easier (especially to Linux) I do think people outside of our tech circle get forgotten about.
For example $100 might be pocket money for us but we do need to remember that not everyone in the world has that luxury. I think sometimes peoples obsession with making pretty things with Electron leads them to forget about people on low income or countries where computers are expensive resources.
There's also an argument to be made for how native applications are generally better for people who depend on accessibility features too.