Why HN does not support 2FA?

The only risk is spam, which can already happen via sophone 2fa phone numbers or TOTP libraries. HN already has significant spam filtering, so 2FA has close-to-zero upside and increases the complexity of the community. It's not like HN accounts are used to process pitch decks/payments through ycombinator, and I guarantee those ycombinator credentials have 2FA.

I will take this as a serious request. The likelihood that anyone would bother to try and access someone else's account would be almost non existent to remote for the fact most here would be using fairly good long passwords given the nature of the site.

Are there or have there been members who have claimed that they didn't write replies here and someone must have hacked their operating system?

HN is not interested in spending money in these ways.