The only reason it worked for youtube is that they were the only service offering reliable high quality video. Other video hosts had problems with loading times

The only reason it worked for youtube is that they were the only service offering reliable high quality video. Other video hosts had problems with loading times and reliability. Youtube is arguably a more valuable service in that it takes way more infrastructure to run a video hosting site than it does to run what is essentially, a simple blog. It would probably take no more than a year of development experience to build a site like Medium(leaving out scaling concerns). Youtube, on the other hand is a beast. I can't even imagine beginning to build an application like youtube. Youtube can push ads hard without bleeding users because they offer quality so many orders of magnitude higher than the alternatives. Medium has only one thing to offer: nice design.