If you think of webinars more like conference talks (and less like sales events), it makes it easier to understand why they're useful. Teaching at scale.
Conferences are platforms that do the marketing for you with the trade-off that you may not get accepted.
Once you (or your advocates) have an established audience though, you don't need permission to host an event. Platforms like Crowdcast make it easy to set up and send out invites to register.
Do your talk as you normally would, but now you can do it as much (or as little) as you want!