Some people love saying Mastodon/OStatus is very scalable because of federation but let's be honest that's some bullshit. It's easy to split and multiply, but that's not scaling.
The birdsite is much easier to scale.
Just imagine one edge case we're not seeing for now: many people using it (let's say millions) and following a very famous person
That person must have their own instance at this point, at least.
... what happens when they toot?
just imagine the enormous peaks and lag it'll do. And we're not even talking about media.
How would Mastodon realistically handle Katy Perry? I have no idea.
@CobaltVelvet I think the on-boarding process might be a hitch, too. The main instance needs to be available enough that Katy Perry can just wander by and set it up on a whim and start tooting; right now there's a bunch of confusing decisions to make right off the bat. The penalty for getting it wrong is relatively low, but for some people, they won't stick it out through the first migration.
Or maybe Katy's IT guy will make a bespoke instance for her and that'll be that.