Surely containers make it far easier to deploy/distribute maintained software as it makes it so much easier for people to switch to a newer version without needing to worry about incompatible versions of libraries etc. that can break something else. It can be used for pinning a specific older version of software for "reasons", but I think that's less common.

Consider people using a containerised NgINX webserver as a reverse proxy - it's so much easier to keep it up to date compared to using a distribution's version of NgINX.