Notice the wording on a 1988 WT about the action of turning in a field service report:
"This will demonstrate his affiliation with the theocratic organization of Jehovah's Witnesses and his submission to it"
It's all about "submission" to an organization, that's pretty clearly stated.
Then comes the punchline in parentheses:
"(This would also be true of all others turning in field service reports.)"
So that's it, if you turn in a field service report you're acknowledging your submission.
And isn't that just how the GB likes it.
Our being meek little good do-bees submitting to their organizational rules?
Not turning in your purported time means you're not being submissive to them.
*** w88 11/15 p. 17 par. 9 Helping Others to Worship God ***
9 The two elders will inform the student that when he qualifies for and shares in the field service, he may turn in a field service report and a Congregation’s Publisher Record card will be made out in his name. This will demonstrate his affiliation with the theocratic organization of Jehovah’s Witnesses and his submission to it. (This would also be true of all others turning in field service reports.) The discussion should also cover Bible counsel, such as is outlined on pages 98 and 99 of Organized to Accomplish Our Ministry. Hence, this would be an appropriate time for the student to obtain a personal copy of that book.