(or can they only use the chat to ask questions?)

That's not true webinar style. It's like the meetings (more than two people) are being punished by time limits and we don't even get the benefit of true webinar style (when you can't see anyone but the presenter.)

I meet all time with groups of 3-15 and it's not a webinar at all.

Our focus is collaboration and engagement during webinars. We feel our webinars are a better webinar style than traditional other platforms which limit attendee engagement (and some your audience can only watch!). We provide opportunity for everyone to engage in the event with video and audio. It is up to the host how they manage this, a good way is to use the raise hand feature during Q&A panel discussions. If you don't want anyone else to join of course, you can lock everyone as audience only with just chat, Q&A or polls for the audience - it all depends on your use case, the flexibility is there.