The biggest problem I see is the existence of obscure coins that no one even recognizes. Total market cap is not 200B, it's maybe 150B, just forget all the sh-coins.
The second problem is that general population is not particularly bright.
This is not offensive, this is just an observation and developers need to understand this.
Why are the masses not joining Steemit? Because it's complicated!
Ok, open account, wait, now what? Typing is difficult, you have no idea about the ecosystem, rewards are poor (if you have no idea what to do).
The third problem is fundamental: people don't want to do extraordinary things. They don't want to learn what is PoS, hash, markdown... And even if they have the technology, they still avoid using it.
Imagine you have a machine that can take you 1000 km in a single day, so you can experience something extraordinary. Would you use that amazing technology? Well... You probably have it... It's a car!!!