the more experienced you get, the faster you solve basic problems. an experienced reader is much faster than an inexperienced one, even though the text itself contains the same exact information for both.
blitz is about intuition, knowing without looking that certain things tend to end badly for you, and some others tend to end well. slow chess is (more) about taking your time and calculating exactly how it'll turn out.
Ratings are relative to the pool of people being rated.
I'd have to think about this, but for CC vs Blitz I would expect that Blitz games will tend to have more unexpected losses. How that rolls out in the ratings forumula I'm not sure. Perhaps it does bring the whole ecosystem down-or perhaps its mathematically neutral.
Regardless there are far too many variables to compare CC vs Blitz ratings and draw any conclusions.