I think it was mostly aimed at retailers, too.
Paizo's sale of PDFs and direct subscriber PDF benefits is a stone in the shoe of many store owners. The vast majority sell Paizo products anyway, but many grumble about it.
If WotC's only relationship with FLGS owners was their selling D&D books? WotC would sell direct to customers, too.
Of course, that isn't their main relationship at all. WotC has a critically important relationship with FLGS owners who sell M:TG. That sales relationship changes everything - and dominates every aspect of their relationship with store owners. WotC no longer attends at Gencon for the same reason: (other than DDB) -- they don't want to sell direct to fans because they have promised FLGS owners that they won't. WotC won't compete with their retail partners.
DDB ended up working out for them far beyond expectations. It's been an unexpected great success, but it was never the reason for not selling PDFs. WotC's prolonged absence from Gencon tells you all you need to know.
Whether DDB is seen by store owners as competition subsequent to WotC's purchase of it is unclear. I haven't heard or seen any shop owners complain about it like they do with Paizo though. Perhaps that's the real point. Close to the line - but not over. Not yet anyways.