“big, scalable systems” should not be conflated with “centralized platforms” as well.
For example with relays, there are many reasons people might want a scalable and high-performance option.
Aggregators will exist to do search because local search is almost useless for anything that is out-of-network. There will be projects that want to store huge libraries. Certain relay providers will become large as they have expertise that many others don’t.
Scalable and reliable systems if designed right also bring many benefits even if you run at smaller scales, by being more efficient, and taking less time to maintain.
And sometimes you don’t benefit from everything. If you are building a personal notes app, decentralization or all the other Nostr benefits do not matter and come at a significant cost since you’re the only user seeing it and can self-host it.
In that case you want *data portability*