I feel like this narrative is especially untrue for things like lzma where the only dependencies are memory and CPU, and written in a stable language like C. I've had similar experiences porting code for things like image formats, audio codecs, etc. where the interface is basically "decode this buffer into another buffer using math". In most cases you can plop that kind of library right in without any maintenance at all, it might be decades old, and it works. The type of maintenance I would expect for that would be around security holes. Once I patched an old library like that to handle the fact that the register keyword was deprecated.
C is not stable, CPU microarchitecture versions are coming from time to time. LZMA compression is not far from trivial. the trade-offs made back then might not be the most useful ones now, hence there are usually things that make sense to change even if the background math will be the same forever.
sure, churn and make believe maintenance for the sake of feeling good is harmful. (and that's where the larger community comes in, distributions, power users, etc. we need to help good maintainers, and push back against bad ones. and yes this is - of course - easier said than done.)
Smaller boundaries are likelier to need less maintenance, but nothing stands still. The reason you can run an ancient simple binary on newer systems is that someone has deliberately made that possible. People worked to make sure the environment around its boundary would stay the same instead of drifting randomly away with time—usually so doggedly (and thanklessly) that we can argue whether that stability was really a result of maintenance or just a fact of nature.
