What is vBulletin used for?

Hello everyone! I am student researching on evolution online community software. I have come across vBulletin frequently in my readings. It is a popular forum tool. I'd love to know:

• What type of organizations choose vBulletin over free alternatives like DIscourse?

• Is the tool mainly used for legacy support of older communities?

• Is it still used by high-traffic community hubs?

• How popular is vBulleting in different industries like gaming, tech support, d2c etc.?

Any insights will be greatly appreciated. I have to submit my report before 25th of May.