Many Arabic-speaking countries already have very high literacy rates. Meanwhile Somali is a related language officially written in the Latin alphabet, but Somalia has a literacy rate around 50%: https://ourworldindata.org/grapher/cross-country-literacy-ra...

So adopting Arabizi without increasing access to education can be expected to do roughly nothing for literacy, whereas with a good education system, people can learn to read and write in Arabic script just fine.