The instance I use is ran by a bunch of Unix nerds, so I'd expect them to wear their uptime as a badge of honour. I suspect there's probably a sweet spot for instance size, where it doesn't hit the biggest scaling problems, but big enough to justify the ongoing effort, rather than obviously being a one-man shop that will vanish when his cheque to Digital Ocean bounces.
Ahhh, defending reddit because lemmy.world is the target of constant ddos attacks? Just go to a different instance. Lemmy's not closed. A single entrance is just being blocked by assholes who support billionaire-owned platforms.
It's like a mall where the main entrance is closed for construction, but all the other entrances, including the entrances through different stores, are all open.
As a .world user, it's had some instability. Though in general I'd say it has okay uptime for a somewhat startup, volunteer enthusiast run content aggregation & discussion platform.