I've installed fedora thrice last year, and each time, I've had to enable rpm fusion in the terminal and download ffmpeg to get youtube to work. This is something that can't be fixed afaik, because it's a copyright issue.
imecth
At some point you need start cutting stuff or nothing happens and you're the one still maintaining the 32 bit packages 15 years later.
There's plenty of different solutions, but anything that isn't what people already have is gonna upset.
It's one of those changes that will happen sooner or later, bazzite and steam need to figure out a solution because fedora, and other modern distros can't and won't keep dragging around 32 bit libraries forever.
Fedora doesn't enable non free repositories by default, and that's a big deal for new users. Telling someone they need to run commands in the terminal to get their nvidia drivers, or even get youtube working is a problem.
Even if it's out of beta for 26.04, you'll probably want to wait a few releases before giving it a go. It's bound to be quite unstable for a few years.
low-effort
People always underestimate the work that goes into making sure stuff works. These packages need to be built so they add a lot of compile time to the pipeline, these packages have limitations inherent to 32 bits so they also add troubleshooting and bugs. This is time and resources that could be spent elsewhere.
Apparently there's a few problems with the flatpak version, like you can't ~~run gamescope or~~ start a steam big picture session.
That's not the point, dxvk isn't gonna get used at all if the game is running dx12 or native vulkan.
I think the real problem here, for devs anyways, is that you have people that have 8gb and people that have 16gb, and everything in between, which makes optimizing much harder than they'd want unlike a stable target like a console.
Truth is windows has plenty of bugs too, the main difference is that it comes pre installed so you don't have to deal with the install bugs, and you're already acclimated to all its quirks so you don't notice them as much.
As for Mint, it gets recommended a lot because it's stable and looks a lot like windows, but it's old and slow to update to modern standards, you can always go for a more bleeding edge distribution like fedora.