I disagree. It's true that some stuff is better delivered face to face, but it doesn't mean you can't change minds, teach skills and make a difference in webinars as well.
It all depends on how you match your presentation to your audience.
When you're planning your webinar, let's assume you have done the right thing and surveyed your audience beforehand to understand their needs. You might have asked an open-ended question along these lines: "What is the biggest question / problem / concern you have about [this topic]?" How do you now use the survey results in your planning?
Before you start addressing each of the survey questions in turn, consider whether they fall into broad categories, because that will help determine the type of presentation you deliver.
In particular, think about the type of problem the respondents are expressing in their questions. Broadly, the questions can fall into one of five categories. Let's look at each of them, using an example from a survey about time management problems:
1. Identity: The person believes these problems are just part of their nature. For example, in our time management survey, they might say: "It's just not in my nature to be on time for appointments. How can I fix something that's just the way that I am?"
2. Beliefs: The person has a belief about their current approach which is holding them back from changing. In fact, they don't want to change, because they believe it will have some negative consequences. For example, with time management, they might say: "I have to look busy all the time; otherwise it will look like I'm not working hard enough."
3. Skills: The person wants to change, but doesn't know how to do so. In our example, they might say: "What is the best way to prioritise my daily tasks?"
4. Behaviour: Now they not only want to change, they've tried to make the change. But for some reason, their behaviour doesn't match their desire. In our example, they might say: "I've read all the books and gone to all the courses. But I just can't seem to put it into practice."
5. Environment: Finally, they might be in a situation where they think everything would be fine except for their current situation. In our example, they might say: "I do everything right and seem to have my time management sorted out, but invariably my boss drops off a new job on my desk right before I leave - and that throws me off completely.
What can you change?
The benefit of classifying your survey responses this way is that you now know what sort of problems the audience is facing, and whether you can solve them.
For example, if you're a motivational or inspirational speaker, you will often be working at the belief level, persuading their audience to change their way of thinking. However, be aware that this can be difficult - although not impossible - on a webinar. On the other hand, if your audience already has the right beliefs and is just lacking the skills, it might be better to offer a training webinar to teach new skills and to reinforce them with interactive exercises (behaviours).
The same applies the other way around. If your webinar is about time management techniques, you're teaching skills and behaviours. But your material will fall on deaf ears if your audience has limiting beliefs about time management, or - even worse - if poor time management is part of their identity.
As a third example, if you're a manager of a team, and they have all the right beliefs, skills and behaviours, it might turn out that you need to change their environment rather than sending them on a time management course or webinar!
Finally, you might find that your audience's problems are at a level you simply can't match. In that case, it might mean you can't deliver a useful presentation at all! But isn't it better to know that now, rather than fumbling through a boring presentation that doesn't engage them at all?