The problem with using those numbers as-is as an indicator of game system popularity is that Roll20 sucks for non-5e systems and a lot of people have jumped ship to Foundry VTT [1], which has much better mechanical support for various game systems.
Roll20 still has the overwhelming supermajority of the VTT market, Foundry is the Linux of VTTs.
Some of us use d&d beyond with it, some not. I think the dungeon master prefers foundry much more than roll 20.
What it took was the dungeon master saying we shall do this, a session or two to work out the kinks, and one other player who gained expertise enough to explain game play mechanics (e.g., use the x key) to the rest of us (to offload some of that burden from the dungeon master)
Foundry: 7
Roll20: 7
Unspecified: 2
Fantasy Grounds: 1
Discord only, no seperate VTT: 1
Owlbear (never heard of this one before): 2