It's the security aspect. Nothing runs on an island, so there's the entire OS layer, libraries, and everything else. These require regular security upgrades,

It's the security aspect. Nothing runs on an island, so there's the entire OS layer, libraries, and everything else. These require regular security upgrades, as vulnerabilities are discovered. Eventually, things are deprecated. Python, php and so on, have versions that are end of life. And so, you have to upgrade to an entire new stack. Often that requires upgrade to frameworks, and therefore code. And beyond that, there's uptime monitoring. Security alerts. Logs to be read. Bandwidth and bare metal costs are trivial, compared to labour to keep such things operational. I wouldn't be surprised if one of two things happened. Some piece is now obsolete, and that requires a large amount of work to upgrade. Maybe a partial code rewrite. Or someone key left. And training isn't seen as worth the effort, when #1 is close on the horizon.