Yes, as far as I can tell, there is nothing in the rubrics permitting vernacular only readings. Ultimately it's an innovation.

Having the epistle and Gospel in the vernacular became the norm with the changes introduced on Advent Sunday 1964, or Lent 1965, depending on the local bishops.

There may have been indults/concessions for France, and other countries, before that.

Permission for the use of the vernacular for parts of the Mass had been granted on occasion long before the papacy of Pius XII; including in 1906 by Pius X (parts of Yugoslavia), Benedict XV in 1920 (Croatian, Slovenian, and Czech), Pius XI in 1929 (Bavaria).[3]

Under Pius XII, the Sacred Congregation of Rites granted permission for the use of local languages in countries with expanding Catholic mission activities, including in Indonesia and Japan in 1941–2. In 1949 permission was granted for using Mandarin Chinese in Mass except for the Canon, and for the use of Hindi in India in 1950. Permission was also granted to use a French (1948) and German (1951) translation for rituals other than Mass.[3]

As a means of increasing the participation of the congregation in the celebration of Mass, recognizing that joining in chant is not possible at a Mass that is "read" rather than sung, in 1958 Pius approved the use of hymns in the vernacular at appropriate points in the service.[4] As a means to closer awareness by the congregation he also allowed the epistle and gospel to be read aloud by a layman while the celebrant read them quietly in Latin.[5]

Though insisting on the primacy of Latin in the liturgy of the Western Church (cf. Mediator Dei, par. 60), Pius XII approves the use of the vernacular in the Ritual for sacraments and other rites outside the Mass. All such permissions, however, were to be granted by the Holy See, and Pius XII strongly condemned the efforts of individual priests and communities to introduce the vernacular on their own authority. He allowed the use of the vernacular in other rites and sacraments outside the Mass,[6] in the service for Baptism and Extreme Unction.[7]