We’ll, he’s correct that Social-democracy is a capitalist concept and that it’s benefit stem primarily from the redistribution-lite done through progressive taxation. Marxist critics claim this redistribution-lite reduces inequality, pacifies the working class and thus safeguards capitalism and those on the top of the pyramid, which isn’t that far off.
The key problem is scaling.
To quote the late David Graeber - who was a far left intellectual but walked the walk and had some really thought-provoking ideas - we’re all communists at a nuclear family level.
We don’t consider money spent on ones toddler a credit to be paid back (there’s a great Italian movie about this called Alberto Express) and while the marriage lasts more often than not the same principle applies to our spouse.
Outside of our nuclear family, we’re socialists. If our sibling and his/her family lose everything in a natural disaster (something without agency nor stemming from life choices), come to our door locking for a place to stay and we offer them the current Airbnb rate, we’ll probably get punched in the face.
This socialism exponentially drops with ones concentric social circles flowing outwards. The relationship with your extended family, good friends or next door neighbors is often pretty socialist because you may do them a favor (“according to their needs”) for which you do not necessarily require immediate reimbursement but a tacit understanding that they themselves will provide a favor (doesn’t have to be comparable) sometime in the future (“according to their ability”).
The concept also assumes asymmetry and that is the reason why we inherently consider people who arrange their social relationships in transactional terms of total equivalence assholes. Incidentally, living with a neighbor who follows libertarian principles to the letter would be a nightmare and result in him/her being bludgeoned to death in case of a systemic shock to the social system.
This “socialism” of concentric social circles drops to negligible but non-zero amounts for complete strangers and is usually formalized as “common courtesy” and varies from culture to culture (face masks are a good example).
The problem with state socialism is that it destroys by force this concept of social and economic relationships and introduces a preposterous notion that a complete stranger, a “comrade” sometimes living seven time zones away and speaking a different language, has the same position in our societal circle as a, let’s say an extended family member.
This aggressive state meddling in private and social relationships, by introducing the great “leveling” destroy community and family bonds, not to mention the nuclear family. The only arbiter of all relationships - social, personal - is the state.
You cannot feel loneliness when you have a hundred fifty million comrades.
