People register for people
A date and a title tell someone what a session is about. A face and a name tell them whether it is worth their evening. When the speaker carries the topic, a reader stops weighing the subject in the abstract and starts deciding if this particular person is worth listening to, which is usually the real question.
So the speakers section is not a flourish added once the page is finished. It is one of the load-bearing parts. Names, photos, what each person is talking about and when, shown on the invitation, give an online session the standing an in-person conference would take for granted.