Why shouldn't we prefer private parties administer the free speech which is most fitting for their platform, as opposed to overly broad legislation at the national level by a government which doesn't appear like they'll catch up on tech within 5 years?
Pressuring government does not mean that the government will suddenly develop technical expertise. Even if the "right people" are voted into government at every level possible in a simultaneous magical moment, it would still take years for the government to develop its own internal consensus as to the state of problems and solutions & to slowly develop a workforce to administer technical policy. But one must question as to whether this is even in the cards for your respective nation.
In the meantime, if we prefer companies deal with the matter, people who don't like how things are done at least have the mere theoretical possibility of going it another way, assuming your market isn't so unhealthy as to only permit one entity (in which case you have a problem which a non-technical government may be able to deal with). The government issues monolithic force-backed policy, whereas the free market can create a diverse product ecosystem for different kinds of people.
And isn't the authority which is exercised by companies one which is ultimately quite fundamental — the freedom of association? The freedom to not have relations with those you don't want to talk to? Everyone should be free to yell their message on public property, but people should also be free to withdraw from each other if they no longer wish to be related. It is questionable to say that free speech must hinge on whether one party wishes to be related to another, especially when that other party has to maintain their services via expensive engineers.