The problem is that it isn’t this simple. To do this people “just” have to realise they need to install SAFEnetwork, use some different way to install the app than they’re expecting and used to, remember how to start it, etc etc.
I’m not saying people won’t do this, my point is that these seemingly small differences are actually large differences to most people, and that only a relatively small number of people find and install this stuff when it is new (people like us). And that it is actually very hard for us to get them to jump! Plenty of examples: Windows to Linux / facebook to diaspora etc.
Also, many apps these days are social, or if not, are expected to have social features that will make them seem useless or not that good, if they only work on SAFEnetwork, where there are so few people a new user will know to be social with. Hence the value of being able to “migrate” - straddle the two networks - if we can.
So yes, it can happen incrementally, but once the early adopters have switched we risk it stalling and either never taking off on a large scale, or taking a long long time.
If we want mass adoption, all these “barriers” need to be considered and reduced as much as we think is possible without undermining the purpose and value of SAFEnetwork.