This is interesting, but I suspect there is a bias.
Submissions, when they succeed, tend to get many upvotes. Comments also get upvotes, but in average an order of magnitude less. The same applies to replies in comment, which I would guess generally get fewer upvotes (or subcomments to comments other than the top comment).
It seems that the Top 100 users here are the one who are posting stories and that comment rarely, as that would optimize the "leverage" to get a higher H-index.
The H-index is designed such that posts with few upvotes cannot decrease the H-index. Since it is defined as the largest n such that you have ≥n posts with score ≥n, adding another low-scoring post doesn't decrease the H-index.
Submissions, when they succeed, tend to get many upvotes. Comments also get upvotes, but in average an order of magnitude less. The same applies to replies in comment, which I would guess generally get fewer upvotes (or subcomments to comments other than the top comment).
It seems that the Top 100 users here are the one who are posting stories and that comment rarely, as that would optimize the "leverage" to get a higher H-index.