> "i.e scalability and server costs still haven't become an issue at this stage"
What you're describing is a hackathon demo, not a product. When you expect something to go hockey-stick, so simply can't afford not planning ahead with scalability.
Many doesn't and you can see them fail to cope with the stress an unexpected interest pokes their services. (Think mastodon, or any random blog that gets the Hug of HackerNews).
Developers _should_ be aware of this. Shipping features should never be ahead of serving what you offer live.