That is a pretty big misunderstanding of how Facebook operates. If Facebook put advertisers ahead of users, it would not be at 1B users and it would not have been around for 8 years, and dominant for many of those years. The business model is primarily to make people happy to make sure to have their attention, and secondarily to sell ads against this attention.
I've worked at Amazon, Google, and Facebook. The core characteristic of each of these companies is that they are all ruthlessly focused on their primary customer as the user, not as the retailer or the advertiser. And it is for this reason that they get to massive scale and become dominant. If you don't get this, then you won't understand why Parse is a clear fit.
Ah, that ruthless focus on keeping the users and the developer community happy must be why Google killed Reader and will probably kill Feedburner soon, and why so many great products got acquired and then killed by their new owners a few years later.
You're right that if you believe what you just declared, then Parse's future at Facebook seems reasonable. You're also right that we won't convince each other of our views on this, so I guess time will tell whether Parse continues to thrive or gets shitcanned in a few years.
I've worked at Amazon, Google, and Facebook. The core characteristic of each of these companies is that they are all ruthlessly focused on their primary customer as the user, not as the retailer or the advertiser. And it is for this reason that they get to massive scale and become dominant. If you don't get this, then you won't understand why Parse is a clear fit.