This is a sort of shorthand for discouraging people from developing strong, dissident, aberrant or divisive political positions. Discouraging people from taking on political identities in general, other than a unified chinese identity. Discouraging people from disparaging and/or distrusting the government. Keeping fringey social trends out of the mainstream.
If you think of how strong political identities are currently in the US, this is exactly what they are trying to prevent. They want to keep everyone on the same page in terms of political and social norms.
The skeptical take is that the CCP is protecting itself from popular and democratic revolutionary movements.
On the other hand, a country with 1.x billion people and several languages/ethnicities can become a huge hell-hole without social harmony.
This "revolution" thing didn't end that well in Libya, even if they managed to get rid of the old leader. Same with the "democracy" that was re-installed in Iraq and elsewhere.
So, one has to be careful what they wish for.
If I was leading China I'd most definitely want to keep this sort of bizarre thinking out of my country.
Aside from the CCP wanting to maintain its control in-land, there's this little real issue, that 80% the internet is mostly controlled from a handful of companies, all in the hands of foreign nationals (who are all "patriotic" and all reside in countries other than China).
That is, things like search, social media, etc services are not a neutral international ground, but mostly dominated by a single country's companies. Those foreign countries get to siphon the data, dictate what's acceptable, promote their culture, viewpoints and national interests 24/7, censor or bury what they don't like, etc.
So, while lesser countries might bend over and take it, it makes sense for a country that is a superpower in itself, and has billions of people, to take control of its own web and have its own search, social media, etc -- orthogonally to if they censor them or not.
Ask yourselves: if Google, Facebook, Apple and Microsoft where e.g. Russian or Chinese, would the US (as a state and as citizens) be using them them all the same?
We had no issue with Nokia or Toyota. We consume Anime. Lots of companies use Kaspersky despite apparent ties to RU intelligence services. There is some talk of the DoD pulling out from a contract --but that's DoD and I imagine Chinese version of DoD would do something similar.
Neither Nokia not Toyota were relevant on the pipes and on the culture/interest/spying/etc level. It was just buying foreign consumer products. (And neither is Anime an example of that).
None of those things are like using a foreign Google, Facebook, etc.
And even for those (which are entirely time), there were huge worries about the Japanese "buying everything" (in the 80s), and people saying people should "buy American" etc.
EDIT: Not sure why I'm being downvoted, everything I mentioned has been widely reported on and can be confirmed in ten seconds with a Google search.
That's the official version.
It's most probably about rejecting the influences from the West, preservation of Chinese culture. Recently there's also quite a huge war on influence of Korean culture.
I have no beef in this fight, not being an American, but I see the same behaviour from Fox, CNN (probably the biggest offender), MSNBC, Breitbart and sometimes even BBC.
Said another way a bit more reductionist, it seems that any engagement between CNN vs Fox types is rather marginal (for expected outcomes), vs playing both sides and exploiting the cognitive dissonance/norms differential between the two.
I think this chapter in human nature could be described as a conundrum that arises from the allegory of the cave.
In the case of China it is socialism in political policies but very capitalist in economic policies.
Sweden is socialism in the economic sense but politically it values freedom much more than China , you will see this if you notice the differences in tax rates in Sweden vs China.