I really enjoyed reading this. Much like Instagram, which had thousands of users sign up on the first day, if you aren't able to scale because of your skill level, wouldn't that affect usage and lead to comments like: 'The app/site is so slow'?
Twitter famously had a "fail whale" but it didn't stop the company from growing. If you have market demand (and I guess advertising) then you can get away with a sub-optimal product for a long time.
Agreed, but there's still an element of survivorship bias there. Plenty of companies failed as they couldn't keep up with their scaling requirements and pushed the "getting away with a sub-optimal product" for too long a time.
Friendster might fit though: https://highscalability.com/friendster-lost-lead-because-of-...
If it’s just “sign up any time you want and go”, yes, it can go that way.
If it’s “join that waiting list” or “book a call” (for KYC purposes or whatever), you have a buffer.
If user count is more or less constant (most internal websites, for example), it’s probably not an issue.
And so on.