"Read It Later, whose Firefox extension (but not web or iPhone app) actually predated Instapaper,"

http://www.marco.org/2010/05/19/on-read-it-later

Read-It-Later came out in 2007, the mobile application came later.

http://en.wikipedia.org/wiki/Pocket_(application)

Read-It-Later started as an article bookmarking system, and then pivoted to be like Instapaper (article parsing and delivery to a mobile app). Calling Read-It-Later older than Instapaper is like calling Bing older than Google. Bing is an evolution of msn search and Microsoft is older than Google.

Calling Instapaper a simile of Read-It-Later stikes me as misleading.

To call Bing older than Google seems entirely true to me (if nothing else, Bing is the heir to Yahoo search). Google was by no means the first search engine, and didn't transform the market or create one where there was previously none - they simply did it better than everyone else.