True, but small businesses fail all the time for all kinds of reasons. Lack of core members is like the co-op equivalent of the trope where the original owner of a small business sells it to some idiot who makes awful decisions and it all goes down the tubes. It doesn’t really explain why for every 100+ traditional businesses that are started, only like 1 co-op is started (numbers made up, obviously, but it feels that way).
It’s interesting because not knowing exactly how powerful something is feels more realistic. I think the uncertainty has it’s place as a narrative device. One way to mitigate the problem you’re describing would be more liberal use of passive checks, like if the party is facing down a troll, a nature check might reveal it’s a powerful ancient beast. For your 17th level fighter example, a good insight check (or passive insight) would let the DM say ‘dont mess with this guy’ without it breaking immersion too much.