The 2017 RRS has added a new definition (although it is in the Terminology section of the Introduction), two new rules and 20 some instances of clarifying language in relation to the change from using the term "measurer" to the term "technical committee."  In the Introduction, the term Technical Committee refers to the "technical committee appointed under rule (c) and any other person or committee performing a technical committee function."  

RRS (c) states that the organizing authority shall appoint a race committee, and "where appropriate," a technical committee (with the exception that World Sailing may appoint the technical committee as provided in its regulations).   Thus, it's clear that the appointment of a technical committee is in the purview of the organizing authority.  However, new RRS  provides that a technical committee shall be a committee of at least one member and can be appointed by the organizing authority or the race committee.  This expands the authority to the race committee to appoint the technical committee. But note that this seems to be the full extent of who may appoint the technical committee.  It does not appear that an appointment by the class is sufficient.

RRS defines the role of the technical committee, which is to "conduct equipment inspection and event measurement as directed by the organizing authority and as required by the rules."  Beyond being a new directive not seen in the 2013 RRS, this appears to limit who may give directions to the technical committee.  It would seem that the race committee cannot direct the technical committee, so any directive from a race committee is more of a suggestion than an order.

But most importantly, the 2013 RRS mentions "measurer" in just a couple places, with RRS (c) instructing the measurer to report to the race committee if a competitor is believed to have broken (a) or (b), and RRS  instructed the measurer to report to the race committee if the measurer believes a competitor does not comply with the class rules.  The 2017 RRS mentions "technical committee" in about 20 different places, such as extending explicit authority to protest a boat (RRS (a)) and request redress (RRS (b)).

The structure and role of the measurer, now technical committee, is much better defined under the new rules.  Additionally, it would seem they have been given greater autonomy and certainly more authority.  It would seem that, when considering the actions of the technical committee, it is better to now think of them as procedurally an equal party to the race committee and protest committee, with a greater role in assuring fairness than they had under the 2013 RRS.