They are just a lot less work (the platform provider does the bulk of it) so it's not that hard for third parties to support a couple of competing platforms. The barrier part is much less barrier-y than, say, desktop apps or smartphone apps. The space is also smaller and more constrained - nobody is going to invent an 'integration' as popular as, say, a snapchat.
For now most apps are pretty simple, but with better conversation skills (comprehension, keeping context, etc), developers might write some pretty advanced ones. And if one platform has infrastructure that can offload that and convert it into simple APIs, I can see it being a stronger lock-in than smartphone apps.
Agreed. Let's remember how simple apps used to be in the first home computers. $5 on a single floppy, mostly to convert duplication costs. As the market developed, they got more sophisticated and became a larger moat.
I think it'd be hard for anyone to remember that since it didn't really happen. Gates was complaining people were pirating his $75 BASIC pretty much right off the bat, for instance.
