Pacelining groups are more dangerous that a single person an e-bike. We quit doing big, organized rides years ago, because of these wackos. The last straw was one of the biggest century rides on the east coast...very popular because it is almost dead flat. Thousands of people would show up for this thing. There was every level of performance, and experience. The locals would hide for the weekend. The roads were totally taken over by bikes. We did this ride several years in a row. Each year there were horrendous accidents. The last time we saw a guy drop a water bottle into his wheel, and do a face plant, within the first mile. Twenty five miles in, a guy in the middle of a paceline touched the guy in front of him, and shot out perpendicular to the line, into an embankment. My wife, and I, riding along the far right edge of the road, were almost piled into by a ten person line, riding at 30 mph. The fool in the front had his head down, and ten people were counting on him to keep them safe. We both saw them closing fast, in our mirrors, and shouted, "Look out!" He looked up just in time, and they passed us with inches to spare. His ego was clearly shaken, and he yelled at us to get to, "Get hell off the road." Later a helicopter was called in to take away another paceline rider.
Humans have poor judgement. It gets worse in a pack situation. Drafting makes sense for autonomous vehicles, with unemotional computers in charge. It has no place on public roadways. The line is much longer than a single e-bike, the reaction time is multiplied greatly, and the requirement for multiple people to make the right decision, in seconds, makes the chances of error soar.