"what is stopping them from changing their biz model and also start to distribute the coins"

Pride and arrogance from multibillionaires. Multi-billionaires don't think like you. They all think in very specific ways. They don't see Steemit as a threat. They do not see a platform that only has hundreds of millions of dollars in market cap as any significant threat at all. They compete with each other not with the little people.

Multibillion dollar corporations are extremely slow to react but when they do react they react with overwhelming force. Because of their speed they can be dodged if timed right. There is an extreme air and "spirit" of narcissistic solipsism embedded within all large multibillion organizations.

They sit at the tables of presidents, kings, and prime ministers handing down judgements in the form of advice to those leaders. Who then implement them in various laws and trade agreements that benefit them. They bribe with millions of dollars in fast cash easily every day. Steemit is like nothing to them less than nothing.

They will not change their business model. What made the multibillionaires in the past is what they "think" will continue to keep them multibillionaires into the future. Until it doesn't.

"In terms of features/functionality and the whole experience, facebook is light years ahead."

The features are being developed as we speak in real time. All that is required is the sharp mind of a developer that knows what they are doing, and the resolve to see the feature manifest in reality through consistent process of work and iteration over an extended period of time.

"The already have the most important asset, that is the users, the established content, and environment that users are not only familiar with but engrossed in. As soon as SteemIT starts to get any real traction, for giving tokens, they will introduce it too."

The active monthly users of Steemit have been growing month over month. I see no reason for that to suddenly reverse. At any given time steemit has 15,000 to 30,000 active users and the market cap is already huge. Imagine what an extra 20%-30% increase will do to the price of steem and therefore the price of everyone's posts comments and content such as your piece.

I say let facebook, google, microsoft and all other multibillionaires introduce their token. The market will decide what value it has, if any, and for how long. If the big boys just release another version of gift card but call it a smart contract token crypto the market will laugh in their faces.

The bigger you are the harder you fall.