What problems? So you can't collect all the data on your costumers and do with it as you see fit? And when it gets leaked just say: "Oops, sorry"? If for some startups taking private data seriously is a "problem", I want to see them burn in fire.

The more I think about it, the more I feel that if you're a startup, thinking about this from the get-go won't hurt you and won't really cost you.

What I mean by that is, it's easier to build your db and backups to comply with these laws before you have anything set in stone, than after you have any meaningful amount of personal data. Like, if you organise your backups and db to happily be able to handle removal of requested data before you accrue too much technical debt/inertia then you're going to be ahead of anyone who has to retrofit, which in many ways actually puts you at an advantage.

Also, I for one won't be mourning the loss of the business model that parasitically lives of exploiting user data.

Beginning with a partial solution to this problem is better than doing nothing at all. This sad state of affairs has gone on for far too long.