That is kind of true as estrogen doesn’t cause “damage” like alcohol does, but oral estrogen increases risk of blood clots in a way that transdermal estrogen routes don’t.

Also I would warn against taking everything your endocrinologist as gospel since often hormone providers don’t really know that much about trans people specifically. Mine has given me false information several times in the year or so I’ve been with them and asked me how HRT side effects work when I told him he was wrong.

as for the source here’s a wikipedia article and the study behind the citation.