I've absolutely managed to have non-structured zoom meetings which have been productive. Often its just a spillover of standup where me and a coworker take over the end of the meeting and basically let everyone else drop off (or not) and we start bitching about something horrible to fix. Sometimes it resulted in something meaningful, sometimes it was just a bitching session. I did this mostly with other coworkers because I'm an introvert. If you're aggressive about hopping on zooms with other people then they can happen with external people. I've gotten dragged into zooms with customers, via the customer services team airdropping me into some horrible customer issue, which later solidified the direction the architecture should go based on the obvious struggles the customer was having. My coworker at prior job was better about inserting himself into those kinds of virtual discussions.

And there's a major advantage to being able to operate that way since you don't have to be geolocated with your customer or your customer services folks and you don't need plane tickets and you can get it done with an hour or three virtually rather than having to take days out of your schedule to do an onsite.