I've seen it individually recommended in a number of places.
Why? Well unlike (say) GoToMeeting or Webex, you can use it for free (albeit with a time limit). Until recently it had a much more modern, easy-to-use interface than GoToMeeting as well. Also, apparently it's one of the few videoconferencing solutions that works reasonably well in China.
Also, it apparently scales pretty well; one of the groups in my church apparently had nearly 100 people in a zoom.us conference last week. I didn't participate in that one, but there was a distinct lack of "and that was a disaster" comments.
I resisted using zoom for about two weeks, specifically due to the "start a local web browser to work around Safari's security features" disaster; but ultimately, you need to say "no" to every other person who wants to have a meeting with zoom, and eventually I just had to give up and install the client.
(I've been recommending meet.jit.si since it's 1) open-source 2) unlimited time for the free version 3) doesn't need to have a client installed.)
For at least the last two years, almost every "younger" company I've done video calls with have been using Zoom. A few on Hangouts/Meet. The older companies might still be using WebEx or GoToMeeting. But in my corner of the world, Zoom has been absolutely ubiquitous for some time.
Probably it spreads from company to company as people organized video conferences with external companies, introducing the tool to those people, who decide to try it out, etc.
It's grown significantly over the past year or two. It got a big foothold at universities and has been gaining steam. It came at a time when Skype was pretty terrible to use, and the only other major player was Cisco WebEx, which was also pretty bad. Now all these universities are doing classes online, and they're using Zoom because that's what they have.
My biggest complaint is that, for new users, it seems to choose either the wrong speakers or the wrong microphone about 80% of the time. Once that's fixed, it mostly works well. The interface is a bit clunky, but I can usually get it to do what I want without too much trouble.
Source: I've been a mostly happy user of Zoom at a university for two years.
Zoom IPO'd on April 18, 2019, and was winning market share in the Enterprise video conference space at least a year or two before that. They had a much more reliable product with common-sense features like calling-in via phone line to connect to your meeting, as well as a turn-key solution to rigging a room for video-conferencing.
As far as I know other competitors would be Skype (Microsoft) and WebEx, neither of which seemed nearly as polished.
I have experience with both Zoom and WebEx. Zoom (on Mac) has a lot of what I consider to be "bad behaviors" UI-wise, especially around window management. And it's ugly in the way mobile apps that get ported to the desktop are. But it gets the job done, and WebEx is definitely worse in these and other ways. So... /me shrugs
It is probably nr 1 because it still has very clear audio and video while the performance of Skype for Business and Microsoft Teams is dramatic at this moment. And the last two are supposed to be the standard tools in the very large organization that I work for.
