What is the advantage of steem using a blockchain?

I believe in the underlying philosophy of Steem, which is that content producers and curators on social media platforms should be compensated for the value that they create. However, I don't see why using a blockchain is at all advantageous for this purpose.

Firstly getting paid in a crypto currency is far less useful than getting paid in dollars. If i want to cash out my earnings I have to go to an alt currency exchange to convert my steem to bitcoin, then go to a bitcoin exchange like coinbase or circle to convert my bitcoin into dollars that can be moved to my bank account.

I also do not see why a company like reddit or facebook, which use traditional, proprietary databases, could not put aside a fraction of the revenue they accrue from advertising to pay the most prolific content producers in the same fashion as steem without the use of a slower blockchain based application.

While I see steemit being favorable for those in the niche cryptocurrency market, it doesn't seem to add practical value for the majority of individuals for whom it would be far easier to link their bank information to their social media account and withdraw their earnings directly from company that operates the social media platform.

Just wanted to get people's thoughts on the advantages/disadvantages of blockchain for the purpose of social media.