It feels like a Pareto Principle problem. 80% of source control is text files that can be three-way merged as text files, but a lot of hard problems are in that 20% that isn't.

Git does very well at the 80% and with tools like custom merge tools and git lfs/annex and git sparse "cone" checkouts can get pretty close to hitting the 90 or 95% case.

But yeah, so many of those extra tools in that 80 to 90% area are awful to work with because they aren't the default, aren't out the box, are hard to configure and get right. Partly because it always seems like there will be a gap in that 95%-100% window and partly because the use cases that need that 80% to 90% often are only "just 10% of use cases".

(Which is also to say that to survive Jujitsu and Pijul and others seem to have to work to make sure they handle the 80% base case extremely well just to compete with git, they haven't necessarily time to think about the 90% or 100% problem.)

(ETA: And also relates to why game development seems to feel the 20% cases more, because by volume of data game development is certainly closer to a flip of the 80/20 sides with 80% or more large binaries by volume.)