[giraffe_lady]

It's a good default approach and the one I use most of the time.

If you're setting a lot of text, or mixed text especially that has both prose and graphs or data you run into the limitation of the system fonts just not having the full set of characters.

Using text figures and tabular figures correctly for example is one of the main things that makes those complex mixed texts read well and look "professional" and afaik none of the system fonts include all three sets of numbers, even if they're available in that font from other sources. They also mostly don't support small caps, which is better looking than most other ways you can emphasize text for titles or diagram labels. The CSS auto-conversion fallback is not a good substitute imo.

Anyway again it's a great approach for basic text and still a good start for more complex stuff, but not a full solution depending on how much you care about text presentation. But since most websites are mostly text I think you should care a lot.