not necessarily monoculture, but having a culture that prioritizes quality instead of speed can indeed make a dent on this issue.
Discussion
Can't disagree with quality, but that's not the point...
Take iOS and Android, both high-ish quality platforms yet two distinct UX cultures, migrating between them takes effort to adjust.
In nostr multiple paradigms could emerge, I love what nostr:nprofile1qqs2js6wu9j76qdjs6lvlsnhrmchqhf4xlg9rvu89zyf3nqq6hygt0spz9mhxue69uhkummnw3ezuamfdejj7qghwaehxw309aex2mrp0yhxummnw3ezucnpdejz7qg4waehxw309aex2mrp0yhxgctdw4eju6t09uygje4n is proposing (very likely be used by Zapstore) but other designers will do other type of high quality nostr design. Some may just adapt to OS guidelines
Who knows what will come out, I would guess 3 or 4 main design paradigms, as I mentioned mentally "grouping" apps with Niel's UX will be natural.
We can only expect potential agreement on this while nostr is this small