I've definitely encountered cases where a company didn't have an office in states where employees were located. In some of these cases, employees may have been de facto remote but still technically had an office at the company's location. Others though an employee was clearly remote in a different state.

What I can't speak to is what sort of legal presence the company set up in the remote employee state of residence. (An office may not be needed but some sort of legal paperwork may be.)