It makes sense, having to pay sats to post is a decent anti-spam mechanism. One thing I noticed about the reply mechanism is it costs more and more sats to keep posting on the same reply level. I did it once out of excitement, wasn't even trying to spam. Another clever feature.
Even if someone loads up on sats and tries to spam, they're giving away precious sats for nonsense. And SN can always do some kind of moving average based on activity to make malicious behaviour even more costly in terms of BTC.
Very impressed with Stacker News, the email newsletter is one of the few newsletters I get that I actually check out. I was already a Bitcoin supporter but this site really got me on the path of LN and what's possible. Podcasting 2.0 also very cool. In general, kudos and respect to @koob for making something cool, old school, highly performant, etc etc. <3 This site always loads very fast and has never crapped out on me, or had strange UX. <3