^^Okay, no. Mr. Naysayer over here

Christ. lol
Look there's lots of ways that it "works." Maybe they reached out to her and she wanted too much money. Maybe they reached out to her at a point when she might've been in town, they confirmed a date and it fell through. Maybe she didn't want to do the full on LP/AV treatment. Maybe they didn't reach out to her.
There's too many factors to try and say "if you do this, this, and this, you'll get your favorite porn actress on here." They made a suggestion area and I can only imagine how much bullshit got flooded in there to the point they stopped trying to fulfill any of it. Could be wrong! Maybe they still try. But no, constantly saying "BRING VALENTINA BRING VALENTINA" every couple of days in the forum isn't going to get them to go "y'know what? Maybe let's get Valentina."
They don't exactly pay for everyone girl's flight to Prague either, I imagine. That's up to pre-made arrangements and the timing gods.
And to Mr. Naysayer, it seems to me they do their best to bring in new talent and bring back talent that has proven to sell well. Just because the talent you like isn't here at all or every other week doesn't mean they aren't listening. Believe me, a lot of the recent talent has me rolling my eyes every time I see their name for what feels like the hundredth time, but they must have fans because they wouldn't keep bringing them back if they didn't sell. And I have lost a bunch of models I may have been legitimately in love with due to poor sales.
But, hey, maybe thanks to the assholes on the forum they really aren't listening anymore.

Wouldn't surprise me