If schools or coaches are publicly announcing the names of persons they consider are committed, or are announcing the likelihood of a recruit signing with that school or attending that school they are running afoul of NCAA Rule 13.11.2
Before the signing of a prospect to a National Letter of Intent or an institution’s written offer of admission and/or financial aid, a member institution may comment publicly only to the extent of confirming its recruitment of the prospect . The institution may not comment generally about the prospect’s ability or the contribution that the prospect might make to the institution’s team; further, the institution is precluded from commenting in any manner as to the likelihood of the prospect’s signing with that institution. Violations of this bylaw do not affect a prospect’s eligibility and are considered institutional violations per Constitution 2.8.1
http://grfx.cstv.com/photos/schools/belm/genrel/auto_pdf/comp-mediarelations.pdf
If schools are contacting a person after that person has signed an NLI they are violating the NLI Administrative Guidelines
NLI RECRUITING BAN:
Once a prospective student-athlete signs an NLI, all NLI member institutions and conferences must cease
contact with the NLI signee and his or her family members. Any contact in excess of an exchange of a greeting would result in an NLI Recruiting Ban Violation regardless of the conversation. The conversation does not have to result in a recruiting discussion for a violation to occur. It is understandable that a coach from another institution, due to the relationship established during the recruiting process, may want to call or send a note to congratulate the prospective student-athlete for signing his or her NLI. This exchange is permissible but must be timely following the date of signing and must not be more than the congratulatory dialogue
http://www.nationalletter.org/documentLibrary/administrativeGuidelines.pdf
So readers should be aware that colleges that are publicizing commits, and colleges that are making contact after a recruit signs an NLI are acting in the vast minority of cases, and no generally useful conclusions should be drawn from such expectations.
For an underclassman to announce a commitment to MIT (the subject of this thread) or any other school, I can see two justifications. One, the person is seeking publicity/prestige/bragging rights. Two, the person is seeking to stanch (not stimulate) the recruiting process because he/she is totally sold on the school, completely trusts the coach and/or Admissions Office, and doesn’t want distractions.