@never a jw
It's just a wild guess, but it is exactly what I thought of when I first read the 2013 NWT.
The NRSV is unique in that it is a combination of formal and dynamic equivalence, each approach used just when it is called for to produce what the NRSV motto stated was being "as literal as possible, as free as necessary." You can't find another translation like it...that is not until the 2013 NWT showed up.
The NRSV made a controversial choice that failed in almost every major translation that tried it: inclusive language. Part of the reason it failed in other Bible translations was not just because conservative Christians rejected it, but because it couldn't function in formal equivalent approaches. It is hard to incorporate it unless you follow the NRSV's pattern.
The 2013 NWT abandoned the previous word-for-word, formal equivalent approach of the original NWT for one that matches the NRSV, a mixture of formal and dynamic rendering. It also adopted inclusive language, although not as extensively.
These "improvements" to the text match not just some of the unique choices of the NRSV but its cadence as well. Note this comparison of Romans 6.1-3:
NWT:
Consequently, what shall we say? Shall we continue in sin, that undeserved kindness may abound? Never may that happen! Seeing that we died with reference to sin, how shall we keep on living any longer in it? Or do YOU not know that all of us who were baptized into Christ Jesus were baptized into his death?
NWT 2013:
What are we to say then? Should we continue in sin so that undeserved kindness may increase? Certainly not! Seeing that we died with reference to sin, how can we keep living any longer in it? Or do you not know that all of us who were baptized into Christ Jesus were baptized into his death?
NRSV:
What then are we to say? Should we continue in sin in order that grace may abound? By no means! How can we who died to sin go on living in it? Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death?
The NWT not only updates the language but cuts down the wordiness of the sentences. The cadence or rhythmic flow changes. It actually flows...flows like a famous other translation on the market, the NRSV.
Up till now only the NRSV used this combination of rendition that produced a text with concise renderings and inclusive language. Suddenly in five years, the NWT has made the same type of decisions for its revision...on its own with no formal training?
When the NRSV was released in 1989 it caused a stir because no one had thought of making a translation just this way the NRSV committee did. No other Bible version follows the same combination. It's innovative for its "literal as possible, free when necessary" approach and attention to gender-specific and inclusive terms.
Where would a team of non-scholars get the idea to do the same thing? Look again at the passage from Romans above. Where do you think?