Independent of the elections I think social media websites had by this time “perfected” engagement-driven algorithmic feeds and online news had started getting good at optimizing their content for those purposes. And around this time, anecdotally, is when I think a lot of older people started taking the internet more seriously, as real-world services like Airbnb/Uber/Amazon prime (to be fair, started earlier) became popular and middle aged people started using social media more. This, in combination with the polarizing content of the elections, made the internet into the hostile and echo-chambery place it is today. And it also attracted a lot more Government attention leading to things like GDPR (good in theory, bad inasmuch as it led to the current cookie banner bullshit) and link taxes.