Thanks for taking the time to answer these questions. This sheds a light on something that has been a mystery for me.
If I can ask a couple of final follow up questions: What would you propose to fix the useless RC problem? Would a general increase in the cost of each operation make the network more resilient to spam?
One thing I believe will help is localizing cost increases, for example if user XYZ spams 1000 comments in a day, they get way more expensive for that user. This would be done with a curve, so their 6 comment isn't really expensive because they already did 5, but at some reasonable level 25? 50? 100? they start really scaling up. This of course isn't perfect either as you can make multiple accounts easily and for free.
Increasing the effect of RC dramatically and leaning on RC delegation more for sponsoring users and dapp users. This of course isn't easy either.
There is no real simple solution, but what we have now doesn't work. It is trivial to spammers, and new users and dapp users are the only ones really feeling it.
Yes, but also hinder new accounts even more.