Aren't replies also considered tweets? Click on 1 popular tweet and it counts as 10+ tweets due to the replies automatically loading.

Reading posts? 600 would go by very quickly and 6000 could be scrolled through by a power user pretty easily which sucks for a paid account.

Each time a tweet enters your viewport, it's considered a view. If you have 10 tweets visible on your screen, that's 10 from your quota already.