A stream-entrant has Right View about anatta, but it's only upon Arahantship that the last vestiges of residual tendency (anusaya) to think in terms of I (asmi) are eradicated. Hence, perception of anatta is still important to the sekha.
"Do not force others, including children, by any means whatsoever, to adopt your views, whether by authority, threat, money, propaganda, or even education." - Ven. Thich Nhat Hanh
"The uprooting of identity is seen by the noble ones as pleasurable; but this contradicts what the whole world sees." (Snp 3.12)
"To argue with a person who has renounced the use of reason is like administering medicine to the dead" - Thomas Paine