The "sudden shock" approach is a risk mitigation. You have to ask yourself though, what risk were they mitigating?
There's no good answer to that question I can come up with that should make you want to stay at that company.
As a company, we entrust our employees with a lot of agency and access to our systems, networks and data. We do not spy on our employees nor have intrusive systems to prevent them from seeing/copying internal IP.
Therefore, while these operating procedures foster an agreeable environment for our collaborators to thrive and do actual things without too much segmentation, it makes it painful when a hard decision results in people getting suddenly both very angry against the company, and very capable to inflict damage upon it.
There's a lot of companies with IP that can be extracted or systems that can be sabotaged by a bitter employee. There's also the extreme cases of someone who knows they are being fired who can do a shooting/arson/some other extreme scenario.
I'm not saying I agree with the shock approach but there are definitely some generic risks that I don't think paint a bad picture of the company by their existence.