Back in the day, here is Sokovia, there was a local competetitor to Facebook. They had a great start and everything went perfect for them, but it quickly turned out that the technical side was really bad. Sluggish interface, constant outages, etc.
They tried to rewrite the app from scratch two times, and eventually failed.
So yes, making sure you're moving in the right direction at the beginning of your journey is pretty important.
You don't have to overengineer and stay in your shed until you have a complete, feature complete product, but at least make sure, that you're building on the right foundation.
This is actually the same reason Friendster failed in the face of Facebook, pun intended. Friendster simply could not keep up technically and had to shut down. Later, Facebook actually had a more solid technical footing and could scale quickly.
Yes, that's what I meant, my apologies if I conveyed that incorrectly. Friendster's own scale was untenable for them but Facebook was able to handle their own scale much better.
By all means, don’t spend forever agonizing over the perfect schema and never ship. It really does not matter at small scale anyway, DBs are absurdly fast.
Just understand and accept that you are taking on heavy technical debt that will need to be repaid, and that it’s much more difficult to do once you’ve already vertically scaled several times along the way.
If your selling point is consolidating apps, you absolutely have to get the data model right, else you don't solve the problem. Just because you don't go in and sell it that way, doesn't mean it's not important as hell. The very reason it's hard to get apps to interoperate is that each one has it's own data model. If they used one giant data model... it wouldn't be a problem.
Different apps have different technical problems that can be an enabler or a source of never-ending technical debt. Being able to add new features easily, rather than being stuck scaling, could make or break this product.
Case in point of “engineers are not product people”