The magic of Linux, is you can try it yourself, run your own fork and submit patches.
Well it should probably go further and offer more of another kind of magic - where stuff works as user expects it to work.
As for submitting patches, it sounds like you suggest people play around and touch core parts responsible for file system operations. Such an advice is not going to work for everyone. Open source software is not ideal. It can be ideal in theory, but that's it.
LUKS is the one to talk about as the others aren't as good an approach in general. LUKS is the recommended approach.
It looks like there are enough use cases where some people would not prefer LUKS.
Does it look like I advocate for windows? Nah.
Open source is great when it works. "If there is some good patch..." and "Enough pressure and maybe..." is the sad reality of it. Why would people need to put pressure on order for Linux to start supporting features long available in file systems it supports? Why would I, specifically, should spend time on it? Does Linux want to become an os for everyone or only for people experimenting with dangerous stuff that make them lose data sometimes?
Don't get me wrong, Linux is good even now. But there is no need to actively deny points of possible improvement. When they ask you how great XFS is compared to others you shouldn't throw "exbibytes" word, you should first think what problems people might have with it, especially if they want to switch from windows.
And if I want to only encrypt some files? I need to create a volume specifically for that, right? Or I could just use something else.