I suspect most people with that sentiment don't have a mortgage/kids/etc. I have known youngish people who got a very nice severance package back in the day and essentially took a 6 month sabbatical. I don't really see a problem for getting future jobs so much. But it is a loss of significant income (assuming you were well-compensated even if you're still being paid something) and may not have great alternatives for income though, if you're in the position to do so, you can of course travel or whatever.
I've no argument with the severance cash, I'm saying that you can't just revert to a hobby because you have an "income for life."
The uncertainty means you're still out on the job market looking for a real job.
There's perhaps significantly lower total compensation and potential uncertainty. A lot of people just aren't in the position to travel the world (or whatever) for a year. Or even work on an open source project that may or may not even be within the bounds of the non-compete depending in the company.
Any employment gap can be easily explained by saying "I was under a non-compete and being paid garden leave while working on personal projects to keep my skills fresh". It's very common in e.g. the finance world, I believe.