Maybe because there are no real large format sensors with the exception of a few very rare and expensive examples.
That was kind of my point - a handful of actual large format sensors have popped up here and there over the last decade or so, but most have been basically one-off fabs or a few dozen sensors at best as far as I'm aware, and a few different takes on a mechanical scanning backs for still-life/product style photography.
Google is sadly failing me for the closest I've seen for a practical 'full frame' monochrome back, but even that one was only like 100mm x 100mm or something [trimmed down from 4x5, but still a solid bump up in area from medium format crop sensors], and they were still looking for something like $60,000 for a setup a few years back. I would be pleasantly surprised if that price point has moved by a useful degree, but not exactly holding my breath for it. And even if a high quality digital back option does make it to my collection that I like and actually use, I would still split my time between it and film just because I like handling the negatives.
But it really boils down to the point that every from of art relies on making choices in mediums; all mediums are ultimately tools for expression, and all tools have pros and cons to them. The costs of some of those choices can be a limiting factor, if not an outright complete barrier. Market isn't exactly being flooded with sculptors working in larger-than-life marble compared to people doing pieces suited for desktop art...
Different photography goals lead to different choices. 8x10 slide film is probably not 'the most practical' choice for modern sports photography or daily snapshots of your kids, but I still do some sports and wildlife photography on film just because it is a fun challenge. Still haven't lugged the 4x5 out for it, but some day... I can be fairly casual with film snapshots to the point that I often forget my phone is a very capable and practical option for a lot of things I'll point a camera at. But for me the main issue with my phone as a camera is that it just has terrible ergonomics for it.
And for me the biggest factor for my film work is simply "Because I like it". The vast majority of my negatives aren't likely to get printed, but I still enjoy flipping through my collection on a light table and re-evaluating my printing queue.
For me the physical negatives and fun of playing with my old mechanical cameras is more than enough of the goal for me to pick film for most of my photography. And given that I barely did any photography as a kid I can't really claim my dive down into it is in any shape or form of nostalgia. I would find it a fun and enjoyable practice even if it were a new invention. [But I'm also the type who finds digital fun and enjoyable for its own reasons.]
We have a lot of overlap in possible choices currently. Just a shame that slide film options aren't feeling all that robust.