Tiktok is highly effective as an ecommerce platform, for example. I work with a client who has 90% of their orders coming from Tiktok, and only 10% from their Shopify website. Tiktok allows them to make useful/educational content, get it out quick, and find their buyers.
Tiktok is very efficient as a marketing platform for businesses - if done right.
Lastly, it's just about time spent. People who would have went to the movies, or watched Youtube, or watched a TV show on Netflix are just spending some of that time on Tiktok instead. Do we consider movies, Youtube, Netflix as harming innovation as well?