Meaning of the verb "engage" in context

Question

It was in a TED video. It is at 15 minute and 49 second. Here it goes:

I know that YouTube comments have a very bad reputation in the world of the internet, but if fact if you go on comments for these channels, what you will find is people engaging the subject matter, asking difficult, complicated questions that are about the subject matter, and then other people answering those questions.

It is quite understood that what the speaker means there is to take part in the subject matter by the word engage, but would not it be better to say engage in the subject matter? Or do engage and engage in mean the same thing there, that is to take part in something?

Answer 1

No, not better to say "engage in" there. We engage in {an activity}, whereas we engage {a topic, a subject, a person}.

To engage in an activity is to participate in it, to do it.

After their exams were over, they engaged in some rather riotous behavior.

To engage a subject is to approach it with interest; to engage a person is to address them directly (about something).

She engaged the study of chimpanzees with great zeal.

The interviewer engaged the politician on the subject of global warming.

Now, there are some topics or areas of study which shade into activity, such as study in my example above, and in such cases engage in would also work:

She engaged in the study of chimpanzees with great zeal.

The verb we choose indicates how we are thinking of it, either as something to be learned, a subject-matter, or as the act of learning.