A lot.
First, modern liberalism, whatever that is--and I'd say it's more Progressive Leftism, depends on people being altruistic. That is, individuals are willing to give up their personal views, wealth, economic status, etc., in favor of the group as a whole. Not happening. Not today, not yesterday, not a thousand years ago. People are inherently greedy, narcissistic, and looking out for themselves first and foremost.
Second, and this derives from the first, it requires that everybody be accommodated. No one is left out. Participation trophies for everyone!
If you bother to wade through the OP's article that was linked, Gaston makes a long-winded dissertation that argues for the above. That is, he says a modern liberal society will be inclusive and altruistic. That isn't happening except by force of government. That means it takes a dictatorship of virtue to bring about a Progressive, Leftist, "modern liberal" society.
It also means that society becomes ineffective, chaotic, and crumbles into ruin. Nothing can effectively get done because of the need to be 100% inclusive of everyone's thoughts, feelings, desires, and whatnot. Government becomes a dictatorship deciding how to take from the productive and rich and equalize that by giving to the indolent and lazy. The point of such a society is, first and foremost, for everyone in it to be able to live a child-like existence free from want or worry.
In a working society, the apropos metaphor might be, if you want an omelet, put in the work and you are free to do so, but recognize that you're going to break a few eggs in the process. Nobody's going to hand you one and if you don't put some effort you might starve. No one will particularly care since they know that was your choice.