Hormones often become far less efficient when swallowed due to the processes they undergo before going out to the rest of your body. With estradiol the difference is big because a lot of the estradiol is turned into estriol which is both less efficient as an estrogen and linked to breast cancer

It’s the same with progesterone but I don’t know that any of the metabolites are linked to anything bad. It’s why the experience of oral vs rectal administration of progesterone is so different