For smaller game companies, boxed sets would only work if you use a Kickstarter. Everything paid for in advance. Though a pandemic could come along and cause issues, but what are the odds?
There is the issue of a bad print run (where it's not the printer at fault) and that could be very bad, as you have to push the 'bad books' onto the backers or eat the cost of reprinting a corrected version. That happened to some Kickstarter last year, but I don't recall the details. Nothing I backed or I'd remember it very well.
You'd need a place to store the boxed sets while you mail them out to backers. Some place not prone to floods, or water leaks, or fires.
So, boxed sets, a really cool product with some risk to it versus the POD option. Someone needs to offer a boxed set POD!