I think the interaction over time has definitely reduced, when I came to steemit September last year, the interaction was better, take for instances when you compare introduction posts written last years and compare the interaction of engagement then and now it's definitely totally different, I think this happened as a result of the decrease and deciline in the SBD/STEEM rate from mid April till now.
It wasn't too bad around June, but the engagements and interactions was best around November of last year till march of 2018 And another reason for a significant decline in the engagement and interaction rate would be the the cause of the latest HF20 the introductions of the RC has made it difficult and will continue making it very difficult to interact.
In my opinion interaction has also reduced because of misplaced priorities, people are now more concerned about making money rather than interacting, the dapps has also reduced interactions, people now blog and earn on the dapps and no longer have to interact to also get support.
In a nutshell the interaction on my individual blog Is 4/10 lesser than the 8.5/10 I enjoyed as a September last year till march of this years.
I have noticed the bigger i am getting i am having more interaction. I am someone who comments a lot anyway so will always respond to a reply and normally upvote if I remember.
I think this has not gone unnoticed now and users are starting to follow me more and more as every day I am adding 2 or 3 now.
If you want a score out of 10 rom when i first started I would say in the beginning it was close to zero and maybe a 1 and now I would put it at a 3 to 4 out of 10. The engagement levels are steadily increasing which is a good sign. i am getting worried as I need the votes to say thank you for visiting and commenting on my posts.