In general, the further back you go, the less practical it would be for most people to avoid going into an office if they wanted to remain employed and to avoid doing most of their shopping in-person.
Travel was also significantly less than what it is now. 20 years ago it would have been a local epidemic with limited spread. 10 years ago would have been a pandemic but still limited in terms of spread.
It would have slowed the initial spread, but as we have seen, it only takes a single "superspreader" event to infect an entire country. Out of the various actions taken to fight the pandemic, closing borders was among the least effective. Basically, it only worked on islands and in combination with strong local actions (testing, tracing, quarantine, lockdowns, ...).
20 years ago wasn't the middle ages, air travel was a thing (9/11 was almost 20 years ago). In fact, it wasn't that different than it is today.
The difference is in how the disinformation is propagated. In the past media companies would self censure idiotic or untrue ideas to protect their reputations and while you could find information if you looked hard, the things would tend to spread slowly. Social media doesn’t profit from reputation but from engagement, and untruth is more engaging.
