...democratization of media gives everybody the possibility to express their opinion...
Not if 90% of those media are in the hands of very few "Zuckerbergs".
We see already massive erosion in the free speech. They even admit, that they e.g. censor if someone speaks against mass vaccination.
Other than that, great analysis.
Thanks for your comment.
I partially agree. But one could argue that nonetheless media is democratized. That Zuck, Jack & Co. have such power is a consequence of the network effect. So, it's not a lack of democracy, but just the result of the preferences of users to join social media in huge numbers, and then they accept censorship as long as they perceive the medium as useful and as long as they are not censored themselves. But I think there'll come a watershed moment (e.g. the censoring of a widely famous person or a big personal data leak), and then "users" will leave these centralized media in huge numbers.
The people of the world are definitely able to express there political opinions and engage with their politicians more than they were during the year 2000, and certainly more than the OP's comparison of the Roman Republic.
That being said, I also agree with your point. Censorship is a huge problem. In my (recent) studies of authoritarian states, I've found that governments do not typically implement censorship before the people. An authoritarian government will encourage/fund/organize groups of civilians to promote & demand censorship before they come forward with legislation.
While I'm sympathetic to the free-market idea and believe a company like Facebook can operate however they want (within the law,) I do see their actions as problematic.
Corporatism plays a role here too however. All big tech companies are embedded with government in some way. For example, the Snowden NSA revelations.