Wegner had the basic idea correct but what he couldn’t explain was a mechanism for why plates shifted around.
Because he could not explain a mechanism that would cause the Earths’ crustal plates to shift around his idea was dismissed at the time. He also had rates of movements for his continents that seemed very unlikely – too high. It took another 50 or more years for the current plate tectonic theory to become accepted by geologists. This was the result of more evidence being found including the idea of mantle convection plumes that drive plate movement.