macOS has never been completely virus-proof. But the combination of its UNIX-based security model and it not being an interesting target due to limited market size meant the threat was limited. Especially if you're a savvy computer user and don't download any suspicious binaries.

I think that's still largely the case.

You might not realise this, but macOS actually has anti-virus software built in. It's called XProtect. When Apple discovers malicious software (e.g. the recent Zoom exploit) it will generate a hash that gets downloaded by your computer automatically. macOS continuously scans your computer for binaries matching those hashes and neutralises them.

This is all automatic and is separate from the macOS updates you might be familiar with.

While there are additional anti-virus programs you can buy, I don't think they are worth the performance hit and come with their own security concerns.