It's occasionally useful when you have what I call "misbehaved" applications that have certain picky requirements regarding environment - system libraries (e.g.

It's occasionally useful when you have what I call "misbehaved" applications that have certain picky requirements regarding environment - system libraries (e.g. specific oracle version), absolute path locations, etc. and fulfilling those environmental requirements may conflict with other applications if you installed them both on the same box. Better behaved applications (statically compiled golang apps being one i guess) will not be so dependent upon a specially configured environment. I think it gained popularity originally because this is a big problem on development environments and docker was the first (possibly only) technology to really try to solve it. It doesn't solve the "works on my machine" problem and it doesn't do what it does particularly elegantly, but it gets part of the way there. I think the reason people then ported it on to production was because they liked consistency between environments, not because it is especially well suited to production environments. The creators obviously encouraged people to use it in prod (so now it's "best practice") because there's more money in your prod environment than there is in your dev environment. I still think the whole ecosystem is somewhat shoddily put together and the culture is cargo cultish, so I try to avoid it where possible.