I don’t think that’s it. AI mobile apps support voice conversations. And low literacy is rather a motivation for using AI to generate and summarize text.
There's a whole level of ignorance out there that is honestly dumbfounding to even comprehend. The numbers for numeracy and problem solving are even more horrifying.
(It's for this reason that the most popular apps in the US are algorithmically generated feeds of photos, and often-non-verbal videos shorter than a TV advertisement.)
But, besides that, TikTok became the titan it is today during the pandemic. When everyone was indoors (not outside).
Per Google's quick answer, when searching "When did TikTok get really popular?": "TikTok's global popularity surged in 2020 due to pandemic lockdowns, with consistent growth since 2016, surpassing competitors in downloads by 2018."