The choices are still available; it's just hidden beneath layers and layers of commoditization. Gone are the days when we could grow our own spices. Not really: you just have to move out of the city, to a nice European suburb and you can have a garden. Gone are the days when we could forge our own knives. Again, not really. You have to move to some kind of village, where you have access to the local smithy. Let's talk about a trade-off that most people actually face: in the US, they drive in their oversized cars to a mega-super-market and shop for the week. In Paris, I go to my local bucherie for my meats, my local boulangerie for my breads, my local poissonorie for my seafood, and my local fruit and légume marché for my fruits and vegetables. I shop once every few days. It's a big deal for me. I get really high-quality food at good prices, with a personal touch. You'd lament about not having this choice in most parts of the US.

Yes, computers have reached a new level of commoditization. So much so, that many users just use a smartphone and tablet. It's a lot more convenient than sitting at a terminal and with a cherry MX keyboard. But those choices are very much available; they just aren't available to everyone. If you really wanted, you can even design your own processor die based off RISC-V designs. And yes, you can totally build your own Linux system from scratch: I'd argue that's there's a lot more choice available in this regard. Remember the days of the simplistic GNU Stow? Today, there's Nix, and you can base your entire system on it. And use XMonad, rxvt-unicode and zsh, if you so desired; they're still maintained, last I checked. I'm sure there are packages for eccentric people to design their own cursors. FreeBSD and OpenBSD exist, and are quite viable. You could even base a system on SeL4, if you're into that sort of thing.

I wholeheartedly agree that this kind of commoditization is actively harmful and stifles creativity. Cashiers and librarians are walled into their little interface; in the best case, they might figure out how to play a game of Freecell. It's sad, but this is the price we pay to put multiple little computers in everyone's hands. Choices create fragmentation, and with fragmentation, there's little incentive to keep fixing the bugs on esoteric fragments. Every choice increases the testing burden exponentially, and to avoid special-casing each combination of choices, software ends up being written for the lowest common denominator. The result is something like Linux on laptops today: the defaults are so terrible that you're forced to mess with the touchpad driver to get basic usability.