There is a lot of confusion in that article. Dissemindted Intravascular Coagulation (DIC) is not a pulmonary embolism (a big clot in an important place).
DIC predominantly makes you bleed to death from micro clots all over the place and can complicate any cause of sepsis, and sepsis is what most Covid-19 patients are dying from.
Big clots are a real problem for Covid-19 so anti collagulants ARE being used but you can't use too much to quickly - especially with people who are frail.
(Medical advice from the front line.)