I've attended many Eventbrite events over the years and the service is legit.
As far as I can tell, they focus on smaller, simpler ticketing scenarios versus events with detailed reserved seating charts or complicated menus of sub-events (seminars, breakout sessions, etc.).
Eventbrite is better suited for things like job fairs, art/wine festivals, community events, etc. where a specific seat does not have to be assigned, basically general admission events.
Events that take place in a seated facility are generally handled by the venue's preferred ticket vendor, not Eventbrite. For sure, they are not handling reserved seating events at major venues like football stadiums, baseball parks, concert halls, etc.