Several reasons for the dearth of responses:

1. Time certainly is a factor. The better the article, the more responses, probably, and the more time it takes to respond.

2. There are sooo many articles that are worthy of responses that you have to pick and choose which ones.

3. True, Medium is not Facebook but it keeps a record of your interactions. That has a chilling effect on honest responses to some extent (i guess private messaging gets around that but only to some extent).

4. The volume of responses acts as kind of a measurement of the quality of your article (although not always). The better the article (or comment), the more responses.

5. Claps aren't all that bad, even if they are less than what you are looking for. I am very stingy when handing them out, so, to me, they mean something.

That's why you got a couple from me ;-)