I didn't really think it from this angle. Yeah this is actually looking pretty great for Dapps as they would be able onboard their users (without bringing them to steemit) and that is a pretty good way to empower them.

Can't really agree with your opinion about comments. Its more than a little shortsighted. This is a incentivized system where comments get rewarded. If the comments wern't rewarded then having the 3 second rule could have been justified. In the present incentivized scenario, questioning the idea of 'quality comments' is like questioning what's the point of 'quality posts'.

I am a bit concerned that comment bot and spammers will get a little more leeway this way. I do understand that spammy comments will get through no matter the 3 second or 20 second limitation. Just don't think that empowering them by lowering the time period threshold will help. Obviously this is just my opinion as a steem novice and thus my reasoning might be full of holes.