These conferences have fees, just like predatory journals. They tend to be held in dodgy places in otherwise touristy areas, and most of them are partly or fully online anyway. The cherry on the cake is that attendees can use them as holidays funded by their institution.

I don’t dispute that there are probably orders of magnitude more fake papers than fake conference presentations, just that shifting from journal articles to conference talks won’t help at all. If the incentives shift, current paper mills will just shift with the market.