One thing I didn't quite understand from the article is why the credit tenants, who are paying rents on vacant retail space, wouldn't just sublet their lease to

One thing I didn't quite understand from the article is why the credit tenants, who are paying rents on vacant retail space, wouldn't just sublet their lease to another tenant to claw back some of their rental costs. With my admittedly limited understanding of the matter, I believe this is common in Sweden where I live, and I have anecdotally not observed any notable amount of long-term vacancies of retail space here. Are there some rules prohibiting them from doing so?