Yes, harinama-sankirtana is enjoined by the scriptures. Vishnu himself ratifies it.
Once Nārada asked Lord Viṣhṇu where he does he actually resides. Thus, Lord Viṣhṇu replied:
Padma Purana: Uttara Khanda - 92.23
Then the devotee, with a pleased mind and devoted, should go, taking with him
sandal, flowers, good tāmbūlas to the temple of Viṣṇu and Śiva. Then
having separately offered articles (and modes) of worship like water
for washing the feet, respectful oblation etc., and bowed again, he
should do auspicious things like singing. He should also honour the
good dancers having musical instruments made of bell-metal, lutes,
tabors etc., so also he should honour the singers with fragrant
flowers and tāmbūlas, since they are the forms of Viṣṇu. In the Kali
age penance, sacrifice, gifts made with devotion to the good lord of
the world, always give delight.
O king, I (Nārada) asked, “O lord of gods,
where do you live?”
Viṣṇu, pleased with my devotion then spoke to me
thus:
नाहं वसामि वैकुण्ठे योगिनां हृदये न च ।
मद्भक्ता यत्र गायन्ति तत्र
तिष्ठामि नारद ॥
“I do not live in Vaikuṇṭha, nor in the heart of the yogins. O Nārada,
I stay there where my devotees sing (my praise).”
Further, the Nārada-Pancaratra also considers the Name-chanting as the Supreme.
ksetresu vaisnavesv etad aryavatte bhavisyati nasti visnoh param
satyarh nasti-visnoh param padam
If these holy names are chanted in a holy place in the land of
Aryavarta, they will award one increased benefit. Know for certain
that there is no truth superior to Lord Visnu, and no goal superior
to Him.
Text 200
nasti visnoh param jhanam nasti mokso hy avaisnavah nasti-visnoh
paro-maniro nasti-visnoh param tapah
There is no knowledge superior to the understanding of Lord Visnu, no
liberation superior to association with Lord Visnu, no mantra
superior to the holy names of Lord Visnu, and no penance superior to
surrender to Lord Visnu.
Text 201
nasti visnoh param dhyanam nasti mantro hy avaisnavah. kin tasya
bahubhir mantraih kimjapair bahu-vistaraih
There is no meditation superior to the remembrance of Lord Visnu’s
transcendental name, form, and pastimes. There is no mantra greater
than the holy names of Lord Visnu. Considering this — what is the use
of chanting other mantras in relation to Lord Visnu?
Text 202
bajapeya-sahasraih kirn bhaktir yasya janardane sarva-tlrthamayo
visnuh
sarva-sastramayah prabhuh
What is the need of performing thousands of vajapeya sacrifices if
one is engaged in the devotional service of Lord Visnu? Lord Visnu is
the most sacred of all sacred places and the goal of all religious
performances.
Text 203
sarva-kratumayo visnuh
satyarh satyam vadamy aham dbrahma-sdra-sarvasvarh sarvam etan
mayoditam
I am telling you the truth — Lord Visnu is the actual enjoyer of all
sacrifices. I have thus revealed to you the essence of everything
within the universe
And hence, we have the theological justification behind chanting (hari-nama-samkirtanam).
