Hey Luca,
You are absolutely right.
Companies need to be prepared for the growing scale of applications. They should know how to scale dynamically; these days, most products are able to do so.
I didn't expect this from Medium either. Above all, Medium bugs are very common and keep happening week after week, making Medium very unstable.
Despite having a small tech team, that's not an excuse. They should hire more skilled labor and have good fallback mechanisms.
You are right; they should inform us about the issues, especially when people are affected financially. They will start losing their user base.