This is an excellent question, but more pertinent is the fact that these companies are state-sponsored, state-backed.
The CCP/China views these apps as a serious tool of foreign policy and economic expansion, influence and control.
Imagine if Trump had meetings with Apple CEO and was subsidizing their product, creating worker legislation for them, directing/requiring banks to fund them, using the foreign service to help cut deals and suppress competitors etc., controlling/censoring everything in the AppStore.
This happens everywhere to some extent but it's very real for China.
It would be fine if some 'large, great Chinese companies' started doing some great things but that isn't really the case, this will be a form of economic dumping, state collusion and strategy.
It's a serious issue that 'old economy' Trump is nowhere close to understanding.
We don't want to get hyper-nationalist on the other hand, we can't afford to ignore the real systematic issues either, and only a very firm hand will be able to make a difference. This is in a way the paradox of Trump - he's the only US leader, arguably through bluster and arrogance - to be able to actually stand up to some systematic Chinese intransigence.