"larger group of developers" is the phrase that caught my attention. Humans don't scale well. This is where microservices do become attractive. This service is owned by a small team, and that team makes these types of judgements. It may be very different from how other service is owned and maintained, and that's ok.
From my limited experience you get cross team discussions about unit testing, especially if one microservice has too many bugs in the eyes of other teams giving development a bad reputation or making working with a microservice hard. Especially if it breaks with releases and other teams get paged.
