I've been using cargo-outdated for a long time to track outdated dependencies, but a while back someone (on here?) mentioned that cargo update --verbose is slowly making cargo-outdated redundant. I tried it, and while it was true, I think I was just more used to the output format of cargo-outdated.
But recently when I went on a "update dependencies" rampage, I ran into the issue where cargo-outdated won't work with custom crate registrys, so I began using cargo update [--dry-run] --verbose more, and I noticed that somewhat recently it started doing this neat thing where it tells you which dependencies are being held back due to unmet MSRV requirements.
Nifty! I've been religiously putting rust-version in crates and feeling that I'm probably doing something good, but not really knowing what. But now I know!