Only among those people who are opposed in principle to women in ministry is it necessary to put forth an argument that the list of people in Rom 16 reflect the various house churches and their pastors in Rome.
But let's start with Phoebe as a deacon. The most natural way to read the Greek is that she was a deacon. Those who have this entrenched notion that women could not be deacons are compelled to look for a different reading which they must admit is at least a little strained. Yes, "diakonos" can mean servant, but in Pauline ecclesiological usage "servant" takes on the nuances inherent in "Servant of the Lord" language from the OT, especially in regard to Moses. While non-ecclesiological usage could refer to someone who does menial task, anyone who is referred to as a diakonos in ministry takes on a high status. In fact, according to context, diakonos is often translated as "minister".
Moreover, the fact that Phoebe is listed as a diakonos "of the church Cenchrea," makes likely the diakonos is an official position. This is all the more obvious when we take into account that Paul is giving formal introduction to her to the Roman churches. Such formal introductions were commonly given in letters of referral, which this epistle contains for her. In such letters, the referrer would normally emphasize the referee's official capacity.
If Paul did not mean to imply she held an official church title, then he blundered badly, for his letter of recommendation, as it would have most naturally been read, leaves the Romans with the notion that he falsely inflated her resume. Such blunders are the sort of issues which create distrust, especially since Paul had no personal authority over these Christians (he had done no prior ministry with them, nor had he established any of their house churches).
Furthermore, as Greek scholars often comment, if Paul did not mean to convey Phoebe's status as an ordained deacon of the Church of Cenchrea, he could have easily avoided doing so by using one of the cognates of diakonos, such as the verb diakonew (perhaps as a participle), or the noun diakonia (service).
So yes, the translation can possibly be that she was merely a servant and not a minister/deacon. But who would want to argue such? Only those who have already decided that women could not be deacons.
Cranfield, whose commentary on Romans is unsurpassed for its exactitudes on these kinds of matters concludes, "We regard it as virtually certain that Phoebe is being described as 'a (or possibly "the") deacon' of the church [of Cenchrea].'