I have no idea how comment bots run today, but for anyone only slightly invested, it would mean one additional hurdle (get accounts for actual people who are not using the service), but not a blocker (like captchas: they mostly serve to annoy regular users).

That seems like a pretty large hurdle, compared to today where it seems they're just creating as many accounts as they want. There isn't a single political tweet without a bunch of bot garbage as replies. I assume any name with 8 digits at the end is a bot and an auto-block (and these are all over political tweets), but there are so many more tweets that are highly suspicious once you go in and look at their feed.

It would also exclude venerable people which is the problem with the real name idea

We can imagine a system where twitter checks that person is a real unique human but does not use their personal data for anything else.

Like when they used mobile phone numbers given for security purposes for marketing?

Until the next hack links their real name with their handle? No thanks.

How to verify uniqueness?

*vulnerable, presumably