And then dropped support for it?
I might have gotten into "basic Pathfinder"
It's not so much Basic Pathfinder as an easier introduction for Pathfinder. Instead of "here, read this 576-page rulebook" it's "read this 64-Page Player Book". The idea being people play and get into the game via the Beginner Box and then graduate to the regular game.
It's for financial reasons mostly.
Making books is expensive. Art is a huge cost, with writing and editing also adding to the cost. But once a book has sold a few thousand copies the cost of art, words, and layout is eliminated and you just have to pay for production costs (printing, paper, shipping, storage, etc). So you make more money if you repeatedly sell the same product again and again and again. If you sell 10,000 copies each of
Book X and
Book Y you'll make less money than if you sold 15,000 copies of just
Book X; despite selling a smaller total number of copies the average profit per copy increases.
So if you have two competing product lines, say Pathfinder and Pathfinder Basic you're
more than halving each book's final profit because you're also doubling the related costs.
Competing products are fine so long as the audience is separate or it fills a very different niche. Money I spend buying a board game or card game from WotC or Paizo is money I wouldn't have spent on an RPG book anyway. Money I spend buying a PF Basic book would likely come from money I set aside for RPG books and mean one less regular PF book.
This works to a point, as the budget of your fans is limited, so eventually more products means fewer sales. But hopefully there will be people who buy something like the card game that would not buy the RPG increasing the total number of customers.