[thomasrambaud]

This is true, but APIs are often versionned.

Concerning efficiency this is true CSS / XPath processors, at least, both offer very nice performances.

But download 70KB of HTML each time you only need a single data, where the API request cost only a few (avg < 2KB), can be such a pain if you need to do this frequently. This can be handled by a scalable configuration but I find it a bit the overkill.