Why Pull Upgrade from Production Server Rather than Pushing Them from Development Server?
The primary concern is not giving developers write access to production systems. This goes well with the principle of giving someone the least amount of privileges needed to perform a task.
Giving developers write access to production systems poses a few risks. Developer machines are used to surf the net. It’s expected because developers need to browse documentation, download software, use Stackoverflow etc. There is a slight chance of them getting compromised by malware. This of course spells disaster if the same developer machine has write access to production. Secondly, giving production write access to developers might open them up to the temptation of pushing to production directly, bypassing things like having review systems in place, ensuring all commits pass unit tests etc. This could very well lead to sloppy code which further opens up the application to compromise.