Sure, but I think the point is that it's unlikely the bottleneck will be in the web server, but in whatever database you're using for your logins. Just because

Sure, but I think the point is that it's unlikely the bottleneck will be in the web server, but in whatever database you're using for your logins. Just because you have a single program, it doesn't mean it is required to use a single database. But even if the webserver is the problem, it feels unlikely that you'll end up saving much in infrastructure cost by scaling just the login service rather than just deploying more copies of your webserver. Not saying it is impossible, but it's unlikely for that to be a good justification to adopt microservices. I'm not saying that there aren't good reasons to use microservices, but I agree that scalability is not a good selling point. I'd actually argue that it's harder to build scalable microservices than monoliths.