Need of proof of service for certiorari petition

The procedural requirements in filing original actions before the Court of Appeals is provided in Section 3, Rule 46 of the Rules of Court, to wit:
SEC. 3. Contents and filing of petition; effect of non-compliance with requirements. - The petition shall contain the full names and actual addresses of all the petitioners and respondents, a concise statement of the matters involved, the factual background of the case, and the grounds relied upon for the relief prayed for.

In actions filed under Rule 65, the petition shall further indicate the material dates showing when notice of the judgment or final order or resolution subject thereof was received, when a motion for new trial or reconsideration, if any, was filed and when notice of the denial thereof was received.

It shall be filed in seven (7) clearly legible copies together with proof of service thereof on the respondent with the original copy intended for the court indicated as such by the petitioner, and shall be accompanied by clearly legible duplicate original or certified true copy of the judgment, order, resolution, or ruling subject thereof, such material portions of the record as are referred to therein, and other documents relevant or pertinent thereto x x x

x x x x

The failure of the petitioner to comply with any of the foregoing requirements shall be sufficient ground for the dismissal of the petition. (Emphasis and underscoring supplied)
Admittedly, the Rules require that the petition filed before the CA should include proof of service to the other party. Essentially, the purpose of this rule is to apprise such party of the pendency of an action in the CA. Thus, if such party had already been notified of the same and had even participated in the proceedings, such purpose would have already been served.