among the expert users is there no one able to do an online webinar explaining how to use the system, planning and scheduling of resources?

Yes there are...
It is exactly what we call ... a training session.
Look at our Traning Sessions Calendar...

Of course, these sessions are not free : we cannot propose the software as free and also propose all services as free.
Our business model is based on services.
We choose to propose the software as free so that these is no fee to use it. As a counterpart, all services are paid, including what other editors (that propose paid licenses) will propose as Commercial demonstration.