There are two issues at least. First is working in a country whose government could demand or seize your company-issued equipment, jeopardizing privacy and corporate secrets. Second is tax regulation. If you are an working in a country where your company doesn’t have a presence, suddenly the government can make the case that now there is a reason to tax the company because your working there can constitute presence. So not only would you be potentially liable for taxed earnings but so too your employer. Also some companies have announced that they would adjust compensation in accordance with cost of living, so moving from the Bay Area to Idaho or Belize would no longer be as favorable (I’m sure it would still afford a very comfortable standard of living regardless).

Note that I am not a tax attorney nor an expert on international affairs. These are some things I’ve gathered for why I can’t sit on a beachfront property in Thailand or South America and work.