What is seen on the opposite end are masses of young men and women...
What is seen on the opposite end are masses of young men and women, youth in particular, mesmerized by these speakers and we often witness alongside it a complete devaluation of knowledge. More often than not, what becomes associated with these speakers is a celebrity-like status, and many times a cult develops around them.
Symptoms of narcissism begin to show themselves on social media and mistakes or incorrect conclusions made by these speakers get over shadowed by the justification done for them by the hordes of their fans. The issue is definitely a tough one to tackle, not only because there is the issue of these speakers per say, but also because many times the initial gap between the community and true-scholars indeed does exist.
Furthermore, one would be hard pressed to obtain a religious legal justification to prevent a person from merely speaking or delivering a lecture in and of itself. Arguments can be made supporting this permissibility by the communities themselves, based on different variables, such as lack of scholars in a given area, the crowd-pulling factor that a certain speaker brings, which speaker is admired and liked by the audience, and so on.
Thus, this issue needs to be seen more in light of ethical jurisprudence and in terms of what knowledge truly is meant to be and who it should be attained from. The response that is generally provided is a simple and straightforward one. A religious speaker, or a speaker who wishes to deliver religious knowledge, should generally be someone who has studied in an Islamic seminary, be it in Qom, Najaf or elsewhere.
They should be someone who would generally have a thorough understanding of religious matters - at least in one or two subjects within it, while understanding the depths that exists in other streams. Like with every field, there are institutions where individuals go and study and subsequently become experts in a specific subject.
These institutions are where an individual spends a decent number of years studying the intricate details pertaining to that subject and then after meeting certain criteria is considered reliable enough to be able to comment as an authority.
Which circle of academia would take an individual, who has barely studied a little science or engineering, albeit it be through some of the very same books that the experts have used to study from, to come and lecture on that subject at an academic conference without having any verifiable and credible credentials?