Other VC software is available. It's just that Z**m seems very easy for the novice to use. I've been attending meetings by VC for over 10 years. You can put up presentations for every site to see. If your time is valuable, you really have to price the value added by being out of your office for days or weeks, never mind the carbon footprint of that business class seat.
I agree that some things, such as auditing the behaviour of your suppliers, can only be done in person. No point in telling your customers about the high labour standards of your factory in Bangladesh unless you can drop in unannounced.