Having worked in an IT department in 2020, it wasn't just random. Zoom was stable for large meetings and scaled pretty smoothly up to a thousand participants. And it's a standalone product and it had better moderator tools.
MS Teams often got problems over around 50 to 80 participants. Google Meet worked better but its max was way lower than Zoom (250?). I tried a couple of other competitors, but none that matched up (including Jitsi, unfortunately).
So if you were at an IT department in an organization that needed to have large meetings and were looking for a quick solution that also worked for your large meetings , Zoom was in 2020 the best choice. And big organisations choices means everyone has to learn that software, so soon enough everyone knows how to use Zoom.
They were at the right place, had the better product, gained a dominant position. And now they are tossing all that away. C'est la late stage capitalism!