Why do a lot of people think morde is weak?

I don't get why people think morde is weak, now I might be lower in the ranked system and people might be bad, but there are several challenger, masters, and diamond morde mains in Korea. I think Dong Huap makes good points in this video, how his laning phase is very dominant and he has a good mid game and burst, and if you do win your laning phase you can snowball the lead in other lanes with the dragon, such as bot as long as you coordinate with your jungler. I think the only problem with morde is his horrible mobility, but that makes sense to balance him out, and the in game model. It's honestly really bad to be honest, I just think he needs some loving and people wont think hes garbage anymore.