I don't think there's confusion. I only have total access when the VM is provisioned, but I need to update the dev machine constantly.
Part of what makes a VM work well is that you can make changes and they're sticky. Folks will edit stuff in /etc, add dotfiles, add little cron jobs, build weird little SSH tunnels, whatever. You say "I can know versions", but with a VM, I can't! Devs will run update stuff locally.
As the person who "deploys" the VM, I'm left in a weird spot after you've made those changes. If I want to update everyone's VM, I blow away your changes (and potentially even the branches you're working on!). I can't update anything on it without destroying it.
In constrast, the dev servers update constantly. There's a dozen moving parts on them and most of them deploy several times a day without downtime. There's a maximum host lifetime and well-documented hooks for how to customize a server when it's created, so it's clear how devs need to work with them for their customizations and what the expectations are.
I guess its possible you could have a policy about when the dev VM is reset and get developers used to it? But I think that would be taking away a lot of the good parts of a VM when looking at the tradeoffs.
> What’s the size of the cloud instances you have to run on?
We have a range of options devs can choose, but I don't think any of them are smaller than a high-end laptop.