Eh, I also think it's harmless, and lends a certain "brand" to their posts - which are usually quite good otherwise. Better to be weird than dull, right?
I guess, unless the offputting:goodness ratio gets lopsided and makes people start ignoring them.
Frankly, something about that leading 0 makes me grit my teeth and stop reading. I can't explain why it affects me like that. Perhaps I'm the only one who does, although threads like this seem to pop up whenever they post so I don't think so. If HN had a mute button, I'd probably use it just because it annoys me to that level.
Edit: And now that we're talking about it, they seem to have the need to mention a specific year way more than most, as though deliberately looking for opportunities to draw attention to themselves. Oof. That just made it about 10x more grating to me.
I do get where you're coming from; for me I think it interrupts the way I scan text - a date would be unconsciously absorbed but these stand out as abnormal artefacts requiring full attention.
Yeah, that's a great way of explaining it. Every time, it raises an exception in my mental parser and I have to go back and consciously evaluate it. Then I see that it's the same person who got me yet again, and I grit my teeth.