As a counter-example, someone posted our product on PH and we only noticed when we saw a spike in signups and had a look at where they were coming from. It ended up being #1 that day and still is the main source of signups.
I don't have a PH account myself though and never go to that website, it was pretty bad in terms of design/UX.
The same happened here. One of the mods found our product and put it on PH. We just had a signup button, but there was no activity that a signed in user could do. People still signed up. Who posts your product on PH matters, I think. If we had posted it ourself it would have looked pretty sad.
I don't have a PH account myself though and never go to that website, it was pretty bad in terms of design/UX.