If you are slightly careful and put this service behind a load-balancer/reverse-proxy you can take any given set of end points and turn them into a micro-service when you need to. Sounds perfect for a small team.
Also, the same team spent several hours in meetings deciding whether or not to allow email signup, or facebook signup, or both, or neither, in the mobile app. Then had the same discussions/arguments a few weeks later when a couple new people joined the team.
I realize I sound a bit bitter. I got pushback because I'd used the 'microservice api' in a "we don't like that" language. consuming the api (which I'd understood to be part of the reason of having a central API vs just hitting db tables directly) by anything that wasn't also node was outside the groupthink, and caused problems.
I left the project.
They've got their microservice architecture, but no userbase (yet?) to be concerned about scaling issues.
I understand it's reasonable to be concerned about potential scaling problems, the team/project spent far too much time chasing architectural perfection (and really... 'shiny new stuff') vs executing a marketing plan. It's easier for a group that is tech-folk-heavy to focus on that; I get it. But it didn't solve any problems at hand. But when the mythical "2 million users in an hour" problem happens, it'll probably hold up, unless it doesn't.