You also did not wear a pink and blue striped hat, and did not get an offer. And yet, you seem to not connect your failure to wear a pink and blue striped hat with your failure to get an offer.

I'd suggest you read the section in the article about how you're evaluated. Yes, how optimal your solution is matters -- of course it does. This doesn't mean that you have to get an optimal answer though. You have to do better than the majority of candidates (maybe ~80% of candidates).

For some problems, being in the top 20% of candidate will mean getting the optimal solution. In other cases, it may not. The optimal algorithm might be trivial, and it might be more about coding skills. In another problem, it might be totally unrealistic to expect that a candidate needs to get the optimal algorithm.

Additionally, you seem to assume that since (according to you) getting the optimal answer is necessary, that it must also be a sufficient condition. That's obviously false. It's entirely possible that a candidate needs to get the optimal answer AND implement it well, in which case these other factors come into play.